CImage.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#include "base-precomp.h"  // Precompiled headers

#include <mrpt/utils/CImage.h>
#include <mrpt/utils/CFileInputStream.h>
#include <mrpt/utils/CFileOutputStream.h>
#include <mrpt/utils/CMemoryStream.h>
#include <mrpt/compress/zip.h>
#include <mrpt/math/CMatrix.h>
#include <mrpt/math/fourier.h>
#include <mrpt/math/utils.h>  // for roundup()
#include <mrpt/utils/round.h>  // for round()
#include <mrpt/utils/CTicTac.h>
#include <mrpt/utils/CTimeLogger.h>
#include <mrpt/system/memory.h>
#include <mrpt/system/filesystem.h>

// Universal include for all versions of OpenCV
#include <mrpt/otherlibs/do_opencv_includes.h>

#if MRPT_HAS_MATLAB
#include <mexplus/mxarray.h>
#endif

// Prototypes of SSE2/SSE3/SSSE3 optimized functions:
#include "CImage_SSEx.h"

#if MRPT_HAS_WXWIDGETS
#include <wx/image.h>
#endif

using namespace mrpt;
using namespace mrpt::utils;
using namespace mrpt::math;
using namespace mrpt::system;
using namespace std;

// This must be added to any CSerializable class implementation file.
IMPLEMENTS_SERIALIZABLE(CImage, CSerializable, mrpt::utils)

bool CImage::DISABLE_ZIP_COMPRESSION = false;
bool CImage::DISABLE_JPEG_COMPRESSION = false;
int CImage::SERIALIZATION_JPEG_QUALITY = 95;

static std::string IMAGES_PATH_BASE(".");

const std::string &CImage::getImagesPathBase()
{
        return IMAGES_PATH_BASE;
}
void CImage::setImagesPathBase(const std::string &path)
{
        IMAGES_PATH_BASE = path;
}

// Do performance time logging?
#define IMAGE_ALLOC_PERFLOG 0

#if IMAGE_ALLOC_PERFLOG
mrpt::utils::CTimeLogger alloc_tims;
#endif

/*---------------------------------------------------------------
                                                Constructor
 ---------------------------------------------------------------*/
CImage::CImage(
        unsigned int width, unsigned int height, TImageChannels nChannels,
        bool originTopLeft)
        : img(nullptr), m_imgIsReadOnly(false), m_imgIsExternalStorage(false)
{
        MRPT_START
        changeSize(width, height, nChannels, originTopLeft);
        MRPT_END
}
/*---------------------------------------------------------------
                                Default Constructor
 ---------------------------------------------------------------*/
CImage::CImage()
        : img(nullptr), m_imgIsReadOnly(false), m_imgIsExternalStorage(false)
{
#if MRPT_HAS_OPENCV
        MRPT_START
        changeSize(1, 1, CH_RGB, true);
        MRPT_END
#endif
}

/*---------------------------------------------------------------
                                                Copy constructor
 ---------------------------------------------------------------*/
CImage::CImage(const CImage& o)
        : img(nullptr), m_imgIsReadOnly(false), m_imgIsExternalStorage(false)
{
        MRPT_START
        *this = o;
        MRPT_END
}

/*---------------------------------------------------------------
                                                Copy operator
 ---------------------------------------------------------------*/
CImage& CImage::operator=(const CImage& o)
{
        MRPT_START
        if (this == &o) return *this;
        releaseIpl();
        m_imgIsExternalStorage = o.m_imgIsExternalStorage;
        m_imgIsReadOnly = false;

        if (!o.m_imgIsExternalStorage)
        {  // A normal image
#if MRPT_HAS_OPENCV
                ASSERTMSG_(
                        o.img != nullptr,
                        "Source image in = operator has nullptr IplImage*")
                img = cvCloneImage((IplImage*)o.img);
#endif
        }
        else
        {  // An externally stored image:
                m_externalFile = o.m_externalFile;
        }
        return *this;
        MRPT_END
}

/*---------------------------------------------------------------
                                        swap
 ---------------------------------------------------------------*/
void CImage::swap(CImage& o)
{
        std::swap(img, o.img);
        std::swap(m_imgIsReadOnly, o.m_imgIsReadOnly);
        std::swap(m_imgIsExternalStorage, o.m_imgIsExternalStorage);
        std::swap(m_externalFile, o.m_externalFile);
}

/*---------------------------------------------------------------
                                        copyFromForceLoad

 Copies from another image, and, if that one is externally
  stored, the image file will be actually loaded into memory
  in "this" object.
 ---------------------------------------------------------------*/
void CImage::copyFromForceLoad(const CImage& o)
{
        if (o.isExternallyStored())
        {
                // Load from that file:
                if (!this->loadFromFile(o.getExternalStorageFileAbsolutePath()))
                        THROW_TYPED_EXCEPTION_FMT(
                                CExceptionExternalImageNotFound,
                                "Error loading externally-stored image from: %s",
                                o.getExternalStorageFileAbsolutePath().c_str());
        }
        else
        {  // It's not external storage.
                *this = o;
        }
}

/*---------------------------------------------------------------
                                        copyFastFrom
 ---------------------------------------------------------------*/
void CImage::copyFastFrom(CImage& o)
{
        MRPT_START
        if (this == &o) return;
        if (o.m_imgIsExternalStorage)
        {
                // Just copy the reference to the ext. file:
                *this = o;
        }
        else
        {  // Normal copy
#if MRPT_HAS_OPENCV
                if (!o.img) THROW_EXCEPTION("Origin image is empty! (o.img==nullptr)")
#endif
                // Erase current image:
                releaseIpl();

                // Make the transfer of just the pointer:
                img = o.img;
                m_imgIsReadOnly = o.m_imgIsReadOnly;
                m_imgIsExternalStorage = o.m_imgIsExternalStorage;
                m_externalFile = o.m_externalFile;

                o.img = nullptr;
                o.m_imgIsReadOnly = false;
                o.m_imgIsExternalStorage = false;
        }

        MRPT_END
}

/*---------------------------------------------------------------
                                                Constructor from IplImage
 ---------------------------------------------------------------*/
CImage::CImage(void* iplImage)
        : img(nullptr), m_imgIsReadOnly(false), m_imgIsExternalStorage(false)
{
        MRPT_START

#if MRPT_HAS_OPENCV
        if (!iplImage)
                changeSize(1, 1, 1, true);
        else
                img = cvCloneImage((IplImage*)iplImage);
#endif
        MRPT_END
}

/*---------------------------------------------------------------
                                                Destructor
 ---------------------------------------------------------------*/
CImage::~CImage() { releaseIpl(); }
/*---------------------------------------------------------------
                                                changeSize
 ---------------------------------------------------------------*/
void CImage::changeSize(
        unsigned int width, unsigned int height, TImageChannels nChannels,
        bool originTopLeft)
{
        MRPT_START

#if MRPT_HAS_OPENCV
        // If we're resizing to exactly the current size, do nothing and avoid
        // wasting mem allocs/deallocs!
        if (img)
        {
                makeSureImageIsLoaded();  // For delayed loaded images stored externally
                IplImage* ipl = static_cast<IplImage*>(img);
                if (static_cast<unsigned int>(ipl->width) == width &&
                        static_cast<unsigned int>(ipl->height) == height &&
                        ipl->nChannels == nChannels &&
                        ipl->origin == (originTopLeft ? 0 : 1))
                {
                        return;  // nothing to do, we're already right with the current
                        // IplImage!
                }
        }

        // Delete current img
        releaseIpl();

#if IMAGE_ALLOC_PERFLOG
        const std::string sLog = mrpt::format("cvCreateImage %ux%u", width, height);
        alloc_tims.enter(sLog.c_str());
#endif

        img = cvCreateImage(cvSize(width, height), IPL_DEPTH_8U, nChannels);
        ((IplImage*)img)->origin = originTopLeft ? 0 : 1;

#if IMAGE_ALLOC_PERFLOG
        alloc_tims.leave(sLog.c_str());
#endif

#else
        THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif

        MRPT_END
}

/*---------------------------------------------------------------
                                                loadFromFile
 ---------------------------------------------------------------*/
bool CImage::loadFromFile(const std::string& fileName, int isColor)
{
        MRPT_START

#if MRPT_HAS_OPENCV
        IplImage* newImg = cvLoadImage(fileName.c_str(), isColor);
        if (newImg != nullptr)
        {
                releaseIpl();
                img = newImg;
                return true;
        }
        else
        {
                return false;
        }
#else
        THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
        MRPT_END
}

/*---------------------------------------------------------------
                                                saveToFile
 ---------------------------------------------------------------*/
bool CImage::saveToFile(const std::string& fileName, int jpeg_quality) const
{
        MRPT_START
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);

#if MRPT_OPENCV_VERSION_NUM > 0x110
        int p[3];
        p[0] = CV_IMWRITE_JPEG_QUALITY;
        p[1] = jpeg_quality;
        p[2] = 0;
        return (0 != cvSaveImage(fileName.c_str(), img, p));
#else
        return (0 != cvSaveImage(fileName.c_str(), img));
#endif
#else
        THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
        MRPT_END
}

/*---------------------------------------------------------------
                                                loadFromIplImage
 ---------------------------------------------------------------*/
void CImage::loadFromIplImage(void* iplImage)
{
        MRPT_START
        ASSERT_(iplImage != nullptr)
        releaseIpl();
        if (iplImage)
        {
#if MRPT_HAS_OPENCV
                img = cvCloneImage((IplImage*)iplImage);
#else
                THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
        }
        MRPT_END
}

/*---------------------------------------------------------------
                                                setFromIplImageReadOnly
 ---------------------------------------------------------------*/
void CImage::setFromIplImageReadOnly(void* iplImage)
{
        MRPT_START
        releaseIpl();
#if MRPT_HAS_OPENCV
        ASSERT_(iplImage != nullptr)
        ASSERTMSG_(iplImage != this->img, "Trying to assign read-only to itself.")

        img = (IplImage*)iplImage;
#else
        if (iplImage)
        {
                THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
        }
#endif
        m_imgIsReadOnly = true;
        m_imgIsExternalStorage = false;
        MRPT_END
}

/*---------------------------------------------------------------
                                                setFromIplImage
 ---------------------------------------------------------------*/
void CImage::setFromIplImage(void* iplImage)
{
        MRPT_START

        releaseIpl();
        if (iplImage)
        {
#if MRPT_HAS_OPENCV
                img = (IplImage*)iplImage;
#else
                THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
        }
        m_imgIsReadOnly = false;
        m_imgIsExternalStorage = false;

        MRPT_END
}

/*---------------------------------------------------------------
                                                loadFromMemoryBuffer
 ---------------------------------------------------------------*/
void CImage::loadFromMemoryBuffer(
        unsigned int width, unsigned int height, bool color,
        unsigned char* rawpixels, bool swapRedBlue)
{
        MRPT_START

#if MRPT_HAS_OPENCV
        resize(width, height, color ? 3 : 1, true);
        m_imgIsReadOnly = false;
        m_imgIsExternalStorage = false;

        if (color && swapRedBlue)
        {
                // Do copy & swap at once:
                unsigned char* ptr_src = rawpixels;
                unsigned char* ptr_dest =
                        reinterpret_cast<unsigned char*>(((IplImage*)img)->imageData);
                const int bytes_per_row_out = ((IplImage*)img)->widthStep;

                for (int h = height; h--;)
                {
                        for (unsigned int i = 0; i < width;
                                 i++, ptr_src += 3, ptr_dest += 3)
                        {
                                unsigned char t0 = ptr_src[0], t1 = ptr_src[1], t2 = ptr_src[2];
                                ptr_dest[2] = t0;
                                ptr_dest[1] = t1;
                                ptr_dest[0] = t2;
                        }
                        ptr_dest += bytes_per_row_out - width * 3;
                }
        }
        else
        {
                if (((IplImage*)img)->widthStep ==
                        ((IplImage*)img)->width * ((IplImage*)img)->nChannels)
                {
                        // Copy the image data:
                        memcpy(
                                ((IplImage*)img)->imageData, rawpixels,
                                ((IplImage*)img)->imageSize);
                }
                else
                {
                        // Copy the image row by row:
                        unsigned char* ptr_src = rawpixels;
                        unsigned char* ptr_dest =
                                reinterpret_cast<unsigned char*>(((IplImage*)img)->imageData);
                        int bytes_per_row = width * (color ? 3 : 1);
                        int bytes_per_row_out = ((IplImage*)img)->widthStep;
                        for (unsigned int y = 0; y < height; y++)
                        {
                                memcpy(ptr_dest, ptr_src, bytes_per_row);
                                ptr_src += bytes_per_row;
                                ptr_dest += bytes_per_row_out;
                        }
                }
        }
#else
        THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
        MRPT_END
}

/*---------------------------------------------------------------
                                                operator()
 ---------------------------------------------------------------*/
unsigned char* CImage::operator()(
        unsigned int col, unsigned int row, unsigned int channel) const
{
#if MRPT_HAS_OPENCV

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        MRPT_START
#endif

        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        IplImage* ipl = ((IplImage*)img);

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        ASSERT_(ipl);
        if (row >= (unsigned int)ipl->height || col >= (unsigned int)ipl->width ||
                channel >= (unsigned int)ipl->nChannels)
        {
                THROW_EXCEPTION(
                        format(
                                "Pixel coordinates/channel out of bounds: row=%u/%u col=%u/%u "
                                "chan=%u/%u",
                                row, ipl->height, col, ipl->width, channel, ipl->nChannels));
        }
#endif

        return (unsigned char*)&ipl
                ->imageData[row * ipl->widthStep + col * ipl->nChannels + channel];
#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        MRPT_END
#endif

#else
        THROW_EXCEPTION("MRPT was compiled without OpenCV")
#endif
}

/*---------------------------------------------------------------
                                                get_unsafe()
 ---------------------------------------------------------------*/
unsigned char* CImage::get_unsafe(
        unsigned int col, unsigned int row, unsigned int channel) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        IplImage* ipl = ((IplImage*)img);
        return (unsigned char*)&ipl
                ->imageData[row * ipl->widthStep + col * ipl->nChannels + channel];
#else
        return nullptr;
#endif
}

/*---------------------------------------------------------------
  Implements the writing to a CStream capability of CSerializable objects
 ---------------------------------------------------------------*/
void CImage::writeToStream(mrpt::utils::CStream& out, int* version) const
{
#if !MRPT_HAS_OPENCV
        if (version)
                *version = 100;
        else
        {
                out << m_imgIsExternalStorage;

                if (m_imgIsExternalStorage) out << m_externalFile;
                // Nothing else to serialize!
        }
#else
        if (version)
                *version = 8;
        else
        {
                // Added in version 6: possibility of being stored offline:
                out << m_imgIsExternalStorage;

                if (m_imgIsExternalStorage)
                {
                        out << m_externalFile;
                }
                else
                {  // Normal image loaded in memory:
                        ASSERT_(img != nullptr);

                        const bool hasColor = isColor();

                        out << hasColor;

                        // Version >2: Color->JPEG, GrayScale->BYTE's array!
                        if (!hasColor)
                        {
                                // GRAY-SCALE: Raw bytes:
                                // Version 3: ZIP compression!
                                // Version 4: Skip zip if the image size <= 16Kb
                                int32_t width = ((IplImage*)img)->width;
                                int32_t height = ((IplImage*)img)->height;
                                int32_t origin = ((IplImage*)img)->origin;
                                int32_t imageSize = ((IplImage*)img)->imageSize;

                                out << width << height << origin << imageSize;

                                // Version 5: Use CImage::DISABLE_ZIP_COMPRESSION
                                bool imageStoredAsZip =
                                        !CImage::DISABLE_ZIP_COMPRESSION && (imageSize > 16 * 1024);

                                out << imageStoredAsZip;

                                // Version 4: Skip zip if the image size <= 16Kb
                                if (imageStoredAsZip)
                                {
                                        std::vector<unsigned char> tempBuf;
                                        compress::zip::compress(
                                                ((IplImage*)img)->imageData,  // Data
                                                ((IplImage*)img)->imageSize,  // Size
                                                tempBuf);

                                        int32_t zipDataLen = (int32_t)tempBuf.size();

                                        out << zipDataLen;

                                        out.WriteBuffer(&tempBuf[0], tempBuf.size());
                                        tempBuf.clear();
                                }
                                else
                                {
                                        out.WriteBuffer(
                                                ((IplImage*)img)->imageData,
                                                ((IplImage*)img)->imageSize);
                                }
                        }
                        else
                        {
                                // COLOR: High quality JPEG image

                                // v7: If size is 0xN or Nx0, don't call "saveToStreamAsJPEG"!!
                                const int32_t width = ((IplImage*)img)->width;
                                const int32_t height = ((IplImage*)img)->height;

                                // v8: If DISABLE_JPEG_COMPRESSION
                                if (!CImage::DISABLE_JPEG_COMPRESSION)
                                {
                                        // normal behavior: compress images:
                                        out << width << height;

                                        if (width >= 1 && height >= 1)
                                        {
                                                // Save to temporary memory stream:
                                                CMemoryStream aux;
                                                saveToStreamAsJPEG(
                                                        aux, CImage::SERIALIZATION_JPEG_QUALITY);

                                                const uint32_t nBytes =
                                                        static_cast<uint32_t>(aux.getTotalBytesCount());

                                                out << nBytes;
                                                out.WriteBuffer(aux.getRawBufferData(), nBytes);
                                        }
                                }
                                else
                                {  // (New in v8)
                                        // Don't JPEG-compress behavior:
                                        // Use negative image sizes to signal this behavior:
                                        const int32_t neg_width = -width;
                                        const int32_t neg_height = -height;

                                        out << neg_width << neg_height;

                                        // Dump raw image data:
                                        const IplImage* ipl = static_cast<const IplImage*>(img);
                                        const size_t bytes_per_row = ipl->width * 3;

                                        out.WriteBuffer(
                                                &ipl->imageData[0], bytes_per_row * ipl->height);
                                }
                        }
                }  // end m_imgIsExternalStorage=false
        }
#endif
}

/*---------------------------------------------------------------
  Implements the reading from a CStream capability of CSerializable objects
 ---------------------------------------------------------------*/
void CImage::readFromStream(mrpt::utils::CStream& in, int version)
{
#if !MRPT_HAS_OPENCV
        if (version == 100)
        {
                in >> m_imgIsExternalStorage;
                if (m_imgIsExternalStorage)
                        in >> m_externalFile;
                else
                {
                        THROW_EXCEPTION(
                                "[CImage] Cannot deserialize image since MRPT has been "
                                "compiled without OpenCV")
                }
        }
#else
        releaseIpl();  // First, free current image.

        switch (version)
        {
                case 100:  // Saved from an MRPT build without OpenCV:
                {
                        in >> m_imgIsExternalStorage;
                        if (m_imgIsExternalStorage) in >> m_externalFile;
                }
                break;
                case 0:
                {
                        uint32_t width, height, nChannels, imgLength;
                        uint8_t originTopLeft;

                        in >> width >> height >> nChannels >> originTopLeft >> imgLength;

                        changeSize(width, height, nChannels, originTopLeft != 0);
                        in.ReadBuffer(((IplImage*)img)->imageData, imgLength);
                }
                break;
                case 1:
                {
                        // Version 1: High quality JPEG image
                        CMemoryStream aux;
                        uint32_t nBytes;
                        in >> nBytes;

                        aux.changeSize(nBytes + 10);

                        in.ReadBuffer(aux.getRawBufferData(), nBytes);

                        aux.Seek(0);

                        loadFromStreamAsJPEG(aux);
                }
                break;
                case 2:
                case 3:
                case 4:
                case 5:
                case 6:
                case 7:
                case 8:
                {
                        // Version 6:   m_imgIsExternalStorage ??
                        if (version >= 6)
                                in >> m_imgIsExternalStorage;
                        else
                                m_imgIsExternalStorage = false;

                        if (m_imgIsExternalStorage)
                        {
                                // Just the file name:
                                in >> m_externalFile;
                        }
                        else
                        {  // Normal, the whole image data:

                                // Version 2: Color->JPEG, GrayScale->BYTE's array!
                                uint8_t hasColor;
                                in >> hasColor;
                                if (!hasColor)
                                {
                                        // GRAY SCALE:
                                        int32_t width, height, origin, imageSize;
                                        in >> width >> height >> origin >> imageSize;

                                        changeSize(width, height, 1, origin == 0);
                                        ASSERT_(imageSize == ((IplImage*)img)->imageSize);

                                        if (version == 2)
                                        {
                                                // RAW BYTES:
                                                in.ReadBuffer(((IplImage*)img)->imageData, imageSize);
                                        }
                                        else
                                        {
                                                // Version 3: ZIP compression!
                                                bool imageIsZIP = true;

                                                // Version 4: Skip zip if the image size <= 16Kb
                                                // Version 5: Use CImage::DISABLE_ZIP_COMPRESSION
                                                if (version == 4 && imageSize <= 16 * 1024)
                                                        imageIsZIP = false;

                                                if (version >= 5)
                                                {
                                                        // It is stored int the stream:
                                                        in >> imageIsZIP;
                                                }

                                                if (imageIsZIP)
                                                {
                                                        uint32_t zipDataLen;
                                                        in >> zipDataLen;

                                                        size_t outDataBufferSize = imageSize;
                                                        size_t outDataActualSize;

                                                        compress::zip::decompress(
                                                                in, zipDataLen, ((IplImage*)img)->imageData,
                                                                outDataBufferSize, outDataActualSize);

                                                        ASSERT_(outDataActualSize == outDataBufferSize);
                                                }
                                                else
                                                {
                                                        // Raw bytes:
                                                        in.ReadBuffer(
                                                                ((IplImage*)img)->imageData,
                                                                ((IplImage*)img)->imageSize);
                                                }
                                        }
                                }
                                else
                                {
                                        bool loadJPEG = true;

                                        if (version >= 7)
                                        {
                                                int32_t width, height;
                                                in >> width >> height;

                                                if (width >= 1 && height >= 1)
                                                {
                                                        loadJPEG = true;
                                                }
                                                else
                                                {
                                                        loadJPEG = false;

                                                        if (width < 0 && height < 0)
                                                        {
                                                                // v8: raw image:
                                                                const int32_t real_w = -width;
                                                                const int32_t real_h = -height;

                                                                this->changeSize(real_w, real_h, 3, true);

                                                                const IplImage* ipl =
                                                                        static_cast<const IplImage*>(img);
                                                                const size_t bytes_per_row = ipl->width * 3;
                                                                for (int y = 0; y < ipl->height; y++)
                                                                {
                                                                        const size_t nRead = in.ReadBuffer(
                                                                                &ipl->imageData[y * ipl->widthStep],
                                                                                bytes_per_row);
                                                                        if (nRead != bytes_per_row)
                                                                                THROW_EXCEPTION(
                                                                                        "Error: Truncated data stream "
                                                                                        "while parsing raw image?")
                                                                }
                                                        }
                                                        else
                                                        {
                                                                // it's a 0xN or Nx0 image: just resize and load
                                                                // nothing:
                                                                this->changeSize(width, height, 3, true);
                                                        }
                                                }
                                        }

                                        // COLOR IMAGE: JPEG
                                        if (loadJPEG)
                                        {
                                                CMemoryStream aux;
                                                uint32_t nBytes;
                                                in >> nBytes;
                                                aux.changeSize(nBytes + 10);
                                                in.ReadBuffer(aux.getRawBufferData(), nBytes);
                                                aux.Seek(0);
                                                loadFromStreamAsJPEG(aux);
                                        }
                                }
                        }
                }
                break;
                default:
                        MRPT_THROW_UNKNOWN_SERIALIZATION_VERSION(version)
        };
#endif
}

/*---------------------------------------------------------------
  Implements the writing to a mxArray for Matlab
 ---------------------------------------------------------------*/
#if MRPT_HAS_MATLAB
// Add to implement mexplus::from template specialization
IMPLEMENTS_MEXPLUS_FROM(mrpt::utils::CImage)

mxArray* CImage::writeToMatlab() const
{
        cv::Mat cvImg = cv::cvarrToMat(this->getAs<IplImage>());
        return mexplus::from(cvImg);
}
#endif

/*---------------------------------------------------------------
                                                getSize
 ---------------------------------------------------------------*/
void CImage::getSize(TImageSize& s) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        s.x = ((IplImage*)img)->width;
        s.y = ((IplImage*)img)->height;
#endif
}

/*---------------------------------------------------------------
                                                getWidth
 ---------------------------------------------------------------*/
size_t CImage::getWidth() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return ((IplImage*)img)->width;
#else
        return 0;
#endif
}

/*---------------------------------------------------------------
                                                getRowStride
 ---------------------------------------------------------------*/
size_t CImage::getRowStride() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return ((IplImage*)img)->widthStep;
#else
        return 0;
#endif
}

/*---------------------------------------------------------------
                                                getWidth
 ---------------------------------------------------------------*/
size_t CImage::getHeight() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return ((IplImage*)img)->height;
#else
        return 0;
#endif
}

/*---------------------------------------------------------------
                                                isColor
 ---------------------------------------------------------------*/
bool CImage::isColor() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return ((IplImage*)img)->nChannels > 1;
#else
        return false;
#endif
}

/*---------------------------------------------------------------
                                                getChannelCount
 ---------------------------------------------------------------*/
TImageChannels CImage::getChannelCount() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return static_cast<unsigned int>(((IplImage*)img)->nChannels);
#else
        return 0;
#endif
}

/*---------------------------------------------------------------
                                                isOriginTopLeft
 ---------------------------------------------------------------*/
bool CImage::isOriginTopLeft() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        return ((IplImage*)img)->origin == 0;
#else
        THROW_EXCEPTION("MRPT compiled without OpenCV")
#endif
}

/*---------------------------------------------------------------
                                                getAsFloat
 ---------------------------------------------------------------*/
float CImage::getAsFloat(
        unsigned int col, unsigned int row, unsigned int channel) const
{
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        // [0,255]->[0,1]
        return (*(*this)(col, row, channel)) / 255.0f;
}

/*---------------------------------------------------------------
                                                getAsFloat
 ---------------------------------------------------------------*/
float CImage::getAsFloat(unsigned int col, unsigned int row) const
{
        // Is a RGB image??
        if (isColor())
        {
                // Luminance: Y = 0.3R + 0.59G + 0.11B
                unsigned char* pixels = (*this)(col, row, 0);
                return (pixels[0] * 0.3f + pixels[1] * 0.59f + pixels[2] * 0.11f) /
                           255.0f;
        }
        else
        {
                // [0,255]->[0,1]
                return (*(*this)(col, row, 0 /* Channel 0:Gray level */)) / 255.0f;
        }
}

/*---------------------------------------------------------------
                                                getMaxAsFloat
 ---------------------------------------------------------------*/
float CImage::getMaxAsFloat() const
{
        int x, y, cx = getWidth(), cy = getHeight();

        float maxPixel = 0;

        for (x = 0; x < cx; x++)
                for (y = 0; y < cy; y++) maxPixel = max(maxPixel, getAsFloat(x, y));

        return maxPixel;
}

/*---------------------------------------------------------------
                                                grayscale
 ---------------------------------------------------------------*/
CImage CImage::grayscale() const
{
        CImage ret;
        grayscale(ret);
        return ret;
}

// Auxiliary function for both ::grayscale() and ::grayscaleInPlace()
#if MRPT_HAS_OPENCV
IplImage* ipl_to_grayscale(const IplImage* img_src)
{
        IplImage* img_dest =
                cvCreateImage(cvSize(img_src->width, img_src->height), IPL_DEPTH_8U, 1);
        img_dest->origin = img_src->origin;

// If possible, use SSE optimized version:
#if MRPT_HAS_SSE3
        if (is_aligned<16>(img_src->imageData) && (img_src->width & 0xF) == 0 &&
                img_src->widthStep == img_src->width * img_src->nChannels &&
                img_dest->widthStep == img_dest->width * img_dest->nChannels)
        {
                ASSERT_(is_aligned<16>(img_dest->imageData))
                image_SSSE3_bgr_to_gray_8u(
                        (const uint8_t*)img_src->imageData, (uint8_t*)img_dest->imageData,
                        img_src->width, img_src->height);
                return img_dest;
        }
#endif

        // OpenCV Method:
        cvCvtColor(img_src, img_dest, CV_BGR2GRAY);
        return img_dest;
}
#endif

/*---------------------------------------------------------------
                                                grayscale
 ---------------------------------------------------------------*/
void CImage::grayscale(CImage& ret) const
{
#if MRPT_HAS_OPENCV
        // The image is already grayscale??
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        const IplImage* ipl = this->getAs<const IplImage>();
        ASSERT_(ipl)

        if (ipl->nChannels == 1)
        {
                ret = *this;
                return;
        }
        else
        {
                // Convert to a single luminance channel image
                ret.setFromIplImage(ipl_to_grayscale(ipl));
        }
#endif
}

/*---------------------------------------------------------------
                                                grayscaleInPlace
 ---------------------------------------------------------------*/
void CImage::grayscaleInPlace()
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        const IplImage* ipl = this->getAs<const IplImage>();
        ASSERT_(ipl)
        if (ipl->nChannels == 1) return;  // Already done.

        setFromIplImage(ipl_to_grayscale(ipl));
#endif
}

/*---------------------------------------------------------------
                                                scaleHalf
 ---------------------------------------------------------------*/
void CImage::scaleHalf(CImage& out) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr)

        // Get this image size:
        const IplImage* img_src = ((IplImage*)img);
        const int w = img_src->width;
        const int h = img_src->height;

        // Create target image:
        IplImage* img_dest =
                cvCreateImage(cvSize(w >> 1, h >> 1), IPL_DEPTH_8U, img_src->nChannels);
        img_dest->origin = img_src->origin;
        memcpy(img_dest->colorModel, img_src->colorModel, 4);
        memcpy(img_dest->channelSeq, img_src->channelSeq, 4);
        img_dest->dataOrder = img_src->dataOrder;

// If possible, use SSE optimized version:
#if MRPT_HAS_SSE3
        if (img_src->nChannels == 3 && is_aligned<16>(img_src->imageData) &&
                is_aligned<16>(img_dest->imageData) && (w & 0xF) == 0 &&
                img_src->widthStep == img_src->width * img_src->nChannels &&
                img_dest->widthStep == img_dest->width * img_dest->nChannels)
        {
                image_SSSE3_scale_half_3c8u(
                        (const uint8_t*)img_src->imageData, (uint8_t*)img_dest->imageData,
                        w, h);
                out.setFromIplImage(img_dest);
                return;
        }
#endif

#if MRPT_HAS_SSE2
        if (img_src->nChannels == 1 && is_aligned<16>(img_src->imageData) &&
                is_aligned<16>(img_dest->imageData) && (w & 0xF) == 0 &&
                img_src->widthStep == img_src->width * img_src->nChannels &&
                img_dest->widthStep == img_dest->width * img_dest->nChannels)
        {
                image_SSE2_scale_half_1c8u(
                        (const uint8_t*)img_src->imageData, (uint8_t*)img_dest->imageData,
                        w, h);

                out.setFromIplImage(img_dest);
                return;
        }
#endif

        // Fall back to slow method:
        cvResize(img_src, img_dest, IMG_INTERP_NN);
        out.setFromIplImage(img_dest);
#endif
}

/*---------------------------------------------------------------
                                                scaleHalfSmooth
 ---------------------------------------------------------------*/
void CImage::scaleHalfSmooth(CImage& out) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr)

        // Get this image size:
        const IplImage* img_src = ((IplImage*)img);
        const int w = img_src->width;
        const int h = img_src->height;

        // Create target image:
        IplImage* img_dest =
                cvCreateImage(cvSize(w >> 1, h >> 1), IPL_DEPTH_8U, img_src->nChannels);
        img_dest->origin = img_src->origin;
        memcpy(img_dest->colorModel, img_src->colorModel, 4);
        memcpy(img_dest->channelSeq, img_src->channelSeq, 4);
        img_dest->dataOrder = img_src->dataOrder;

// If possible, use SSE optimized version:
#if MRPT_HAS_SSE2
        if (img_src->nChannels == 1 && is_aligned<16>(img_src->imageData) &&
                is_aligned<16>(img_dest->imageData) && (w & 0xF) == 0 &&
                img_src->widthStep == img_src->width * img_src->nChannels &&
                img_dest->widthStep == img_dest->width * img_dest->nChannels)
        {
                image_SSE2_scale_half_smooth_1c8u(
                        (const uint8_t*)img_src->imageData, (uint8_t*)img_dest->imageData,
                        w, h);

                out.setFromIplImage(img_dest);
                return;
        }
#endif

        // Fall back to slow method:
        cvResize(img_src, img_dest, IMG_INTERP_LINEAR);
        out.setFromIplImage(img_dest);
#endif
}

/*---------------------------------------------------------------
                                                scaleDouble
 ---------------------------------------------------------------*/
void CImage::scaleDouble(CImage& out) const
{
        out = *this;
        const TImageSize siz = this->getSize();
        out.scaleImage(siz.x * 2, siz.y * 2);
}

/*---------------------------------------------------------------
                                        getChannelsOrder
 ---------------------------------------------------------------*/
const char* CImage::getChannelsOrder() const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);
        return ((IplImage*)img)->channelSeq;
#else
        THROW_EXCEPTION("MRPT compiled without OpenCV")
#endif
}

/*---------------------------------------------------------------
                                loadFromMemoryBuffer
 ---------------------------------------------------------------*/
void CImage::loadFromMemoryBuffer(
        unsigned int width, unsigned int height, unsigned int bytesPerRow,
        unsigned char* red, unsigned char* green, unsigned char* blue)
{
#if MRPT_HAS_OPENCV
        MRPT_START

        // Fill in the IPL structure:
        changeSize(width, height, 3, true);

        // Copy the image data:
        for (unsigned int y = 0; y < height; y++)
        {
                // The target pixels:
                unsigned char* dest = (unsigned char*)((IplImage*)img)->imageData +
                                                          ((IplImage*)img)->widthStep * y;

                // Source channels:
                unsigned char* srcR = red + bytesPerRow * y;
                unsigned char* srcG = green + bytesPerRow * y;
                unsigned char* srcB = blue + bytesPerRow * y;

                for (unsigned int x = 0; x < width; x++)
                {
                        *(dest++) = *(srcB++);
                        *(dest++) = *(srcG++);
                        *(dest++) = *(srcR++);
                }  // end of x
        }  // end of y

        MRPT_END
#endif
}

/*---------------------------------------------------------------
                                                setOriginTopLeft
 ---------------------------------------------------------------*/
void CImage::setOriginTopLeft(bool val)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);
        ((IplImage*)img)->origin = val ? 0 : 1;
#endif
}

/*---------------------------------------------------------------
                                                setPixel
 ---------------------------------------------------------------*/
void CImage::setPixel(int x, int y, size_t color)
{
#if MRPT_HAS_OPENCV

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        MRPT_START
#endif

        makeSureImageIsLoaded();  // For delayed loaded images stored externally

        IplImage* ipl = ((IplImage*)img);

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        ASSERT_(ipl);
#endif

        if (x >= 0 && y >= 0 && y < ipl->height && x < ipl->width)
        {
                // The pixel coordinates is valid:
                if (ipl->nChannels == 1)
                {
                        *((unsigned char*)&ipl->imageData[y * ipl->widthStep + x]) =
                                (unsigned char)color;
                }
                else
                {
#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
                        ASSERT_(ipl->nChannels == 3);
                        if (ipl->dataOrder != 0)
                                THROW_EXCEPTION(
                                        "Please, use interleaved images like normal people!!! :-)");
#endif
                        unsigned char* dest =
                                (unsigned char*)&ipl->imageData[y * ipl->widthStep + 3 * x];
                        unsigned char* src = (unsigned char*)&color;

                        // Copy the color:
                        *dest++ = *src++;  // R
                        *dest++ = *src++;  // G
                        *dest++ = *src++;  // B
                }
        }

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
        MRPT_END
#endif

#endif
}

/*---------------------------------------------------------------
                                                line
 ---------------------------------------------------------------*/
void CImage::line(
        int x0, int y0, int x1, int y1, const mrpt::utils::TColor color,
        unsigned int width, TPenStyle penStyle)
{
#if MRPT_HAS_OPENCV
        MRPT_UNUSED_PARAM(penStyle);
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        IplImage* ipl = ((IplImage*)img);
        ASSERT_(ipl);

        cvLine(
                ipl, cvPoint(x0, y0), cvPoint(x1, y1),
                CV_RGB(color.R, color.G, color.B), width);
#endif
}

/*---------------------------------------------------------------
                                                drawCircle
 ---------------------------------------------------------------*/
void CImage::drawCircle(
        int x, int y, int radius, const mrpt::utils::TColor& color,
        unsigned int width)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        IplImage* ipl = ((IplImage*)img);
        ASSERT_(ipl);

        cvCircle(
                ipl, cvPoint(x, y), radius, CV_RGB(color.R, color.G, color.B), width);
#endif
}  // end

/*---------------------------------------------------------------
                                                                                           update_patch
 --------------------------------------------------------------*/
void CImage::update_patch(
        const CImage& patch, const unsigned int col_, const unsigned int row_)
{
#if MRPT_HAS_OPENCV
        IplImage* ipl_int = ((IplImage*)img);
        IplImage* ipl_ext = ((IplImage*)patch.img);
        ASSERT_(ipl_int);
        ASSERT_(ipl_ext);
        // We check that patch do not jut out of the image.
        if (row_ + ipl_ext->height > getHeight() ||
                col_ + ipl_ext->width > getWidth())
        {
                THROW_EXCEPTION("Error : Patch jut out of image")
        }
        for (unsigned int i = 0; i < patch.getHeight(); i++)
        {
                memcpy(
                        &ipl_int->imageData[(i + row_) * ipl_int->widthStep +
                                                                col_ * ipl_int->nChannels],
                        &ipl_ext->imageData[i * ipl_ext->widthStep], ipl_ext->widthStep);
        }
#endif
}

/*---------------------------------------------------------------
                                                extract_patch
 ---------------------------------------------------------------*/
void CImage::extract_patch(
        CImage& patch, const unsigned int col_, const unsigned int row_,
        const unsigned int col_num, const unsigned int row_num) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally

        IplImage* ipl_int = ((IplImage*)img);
        ASSERT_(ipl_int);

        if ((ipl_int->width < (int)(col_ + col_num)) ||
                (ipl_int->height < (int)(row_ + row_num)))
        {
                THROW_EXCEPTION(
                        format(
                                "Trying to extract patch out of image boundaries: Image "
                                "size=%ix%i, Patch size=%ux%u, extraction location=(%u,%u)",
                                ipl_int->width, ipl_int->height, col_num, row_num, col_, row_))
        }

        patch.resize(col_num, row_num, ((IplImage*)img)->nChannels, true);
        IplImage* ipl_ext = ((IplImage*)patch.img);
        ASSERT_(ipl_ext);

        for (unsigned int i = 0; i < row_num; i++)
        {
                memcpy(
                        &ipl_ext->imageData[i * ipl_ext->widthStep],
                        &ipl_int->imageData[(i + row_) * ipl_int->widthStep +
                                                                col_ * ipl_int->nChannels],
                        ipl_ext->widthStep);
        }

#endif
}

/*---------------------------------------------------------------
                                                correlate
 ---------------------------------------------------------------*/
float CImage::correlate(
        const CImage& img2, int width_init, int height_init) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally

        if ((img2.getWidth() + width_init > getWidth()) |
                (img2.getHeight() + height_init > getHeight()))
                THROW_EXCEPTION("Correlation Error!, image to correlate out of bounds");

        unsigned int i, j;
        float x1, x2;
        float syy = 0.0f, sxy = 0.0f, sxx = 0.0f, m1 = 0.0f, m2 = 0.0f,
                  n = (float)(img2.getHeight() * img2.getWidth());
        //      IplImage *ipl1 = (*this).img;
        //      IplImage *ipl2 = img2.img;

        // find the means
        for (i = 0; i < img2.getHeight(); i++)
        {
                for (j = 0; j < img2.getWidth(); j++)
                {
                        m1 += *(*this)(
                                j + width_init,
                                i + height_init);  //(double)(ipl1->imageData[i*ipl1->widthStep
                        //+ j ]);
                        m2 += *img2(
                                j, i);  //(double)(ipl2->imageData[i*ipl2->widthStep + j ]);
                }  //[ row * ipl->widthStep +  col * ipl->nChannels +  channel ];
        }
        m1 /= n;
        m2 /= n;

        for (i = 0; i < img2.getHeight(); i++)
        {
                for (j = 0; j < img2.getWidth(); j++)
                {
                        x1 = *(*this)(j + width_init, i + height_init) -
                                 m1;  //(double)(ipl1->imageData[i*ipl1->widthStep + j]) - m1;
                        x2 = *img2(j, i) -
                                 m2;  //(double)(ipl2->imageData[i*ipl2->widthStep + j]) - m2;
                        sxx += x1 * x1;
                        syy += x2 * x2;
                        sxy += x1 * x2;
                }
        }

        return sxy / sqrt(sxx * syy);
#else
        return 0;
#endif
}

/*---------------------------------------------------------------
                                        cross_correlation
 ---------------------------------------------------------------*/
void CImage::cross_correlation(
        const CImage& patch_img, size_t& x_max, size_t& y_max, double& max_val,
        int x_search_ini, int y_search_ini, int x_search_size, int y_search_size,
        CImage* out_corr_image) const
{
        MRPT_START

        makeSureImageIsLoaded();  // For delayed loaded images stored externally

#if MRPT_HAS_OPENCV
        double mini;
        CvPoint min_point, max_point;

        bool entireImg =
                (x_search_ini < 0 || y_search_ini < 0 || x_search_size < 0 ||
                 y_search_size < 0);

        const IplImage *im, *patch_im;

        if (this->isColor() && patch_img.isColor())
        {
                const IplImage* im_ = this->getAs<IplImage>();
                const IplImage* patch_im_ = patch_img.getAs<IplImage>();

                IplImage* aux = cvCreateImage(cvGetSize(im_), 8, 1);
                IplImage* aux2 = cvCreateImage(cvGetSize(patch_im_), 8, 1);
                cvCvtColor(im_, aux, CV_BGR2GRAY);
                cvCvtColor(patch_im_, aux2, CV_BGR2GRAY);
                im = aux;
                patch_im = aux2;
        }
        else
        {
                im = this->getAs<IplImage>();
                patch_im = patch_img.getAs<IplImage>();
        }

        if (entireImg)
        {
                x_search_size = im->width - patch_im->width;
                y_search_size = im->height - patch_im->height;
        }

        // JLBC: Perhaps is better to raise the exception always??
        if ((x_search_ini + x_search_size + patch_im->width - 1) > im->width)
                x_search_size -=
                        (x_search_ini + x_search_size + patch_im->width - 1) - im->width;

        if ((y_search_ini + y_search_size + patch_im->height - 1) > im->height)
                y_search_size -=
                        (y_search_ini + y_search_size + patch_im->height - 1) - im->height;

        ASSERT_((x_search_ini + x_search_size + patch_im->width - 1) <= im->width)
        ASSERT_((y_search_ini + y_search_size + patch_im->height - 1) <= im->height)

        IplImage* result = cvCreateImage(
                cvSize(x_search_size + 1, y_search_size + 1), IPL_DEPTH_32F, 1);

        const IplImage* ipl_ext;

        if (!entireImg)
        {
                IplImage* aux = cvCreateImage(
                        cvSize(
                                patch_im->width + x_search_size,
                                patch_im->height + y_search_size),
                        IPL_DEPTH_8U, 1);
                for (unsigned int i = 0; i < (unsigned int)y_search_size; i++)
                {
                        memcpy(
                                &aux->imageData[i * aux->widthStep],
                                &im->imageData[(i + y_search_ini) * im->widthStep +
                                                           x_search_ini * im->nChannels],
                                aux->width * aux->nChannels);  // widthStep);  <-- JLBC:
                        // widthstep SHOULD NOT be used
                        // as the length of each row (the
                        // last one may be shorter!!)
                }
                ipl_ext = aux;
        }
        else
        {
                ipl_ext = im;
        }

        // Compute cross correlation:
        cvMatchTemplate(ipl_ext, patch_im, result, CV_TM_CCORR_NORMED);
        // cvMatchTemplate(ipl_ext,patch_im,result,CV_TM_CCOEFF_NORMED);

        // Find the max point:
        cvMinMaxLoc(result, &mini, &max_val, &min_point, &max_point, nullptr);
        x_max = max_point.x + x_search_ini + (round(patch_im->width - 1) / 2);
        y_max = max_point.y + y_search_ini + (round(patch_im->height - 1) / 2);

        // Free memory:
        if (!entireImg)
        {
                IplImage* aux = const_cast<IplImage*>(ipl_ext);
                cvReleaseImage(&aux);
                ipl_ext = nullptr;
        }

        // Leave output image?
        if (out_corr_image)
                out_corr_image->setFromIplImage(result);
        else
                cvReleaseImage(&result);
#else
        THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif

        MRPT_END
}

/*---------------------------------------------------------------
                                                normalize
 ---------------------------------------------------------------*/
void CImage::normalize()
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        IplImage* ipl = getAs<IplImage>();  // Source Image
        ASSERT_(ipl)
        ASSERTMSG_(
                ipl->nChannels == 1,
                "CImage::normalize() only defined for grayscale images.")

        uint8_t min_ = 255, max_ = 1;
        for (int y = 0; y < ipl->height; y++)
        {
                const uint8_t* ptr = reinterpret_cast<const uint8_t*>(
                        ipl->imageData + y * ipl->widthStep);
                for (int x = 0; x < ipl->width; x++)
                {
                        const uint8_t val = *ptr++;
                        if (min_ > val) min_ = val;
                        if (max_ < val) max_ = val;
                }
        }

        // Compute scale factor & build convert look-up-table:
        const double s = 255.0 / ((double)max_ - (double)min_);
        uint8_t lut[256];
        for (int v = 0; v < 256; v++) lut[v] = static_cast<uint8_t>((v - min_) * s);

        // Apply LUT:
        for (int y = 0; y < ipl->height; y++)
        {
                uint8_t* ptr =
                        reinterpret_cast<uint8_t*>(ipl->imageData + y * ipl->widthStep);
                for (int x = 0; x < ipl->width; x++)
                {
                        *ptr = lut[*ptr];
                        ptr++;
                }
        }
#endif
}

/*---------------------------------------------------------------
                                                getAsMatrix
 ---------------------------------------------------------------*/
void CImage::getAsMatrix(
        CMatrixFloat& outMatrix, bool doResize, int x_min, int y_min, int x_max,
        int y_max) const
{
#if MRPT_HAS_OPENCV
        MRPT_START

        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);

        // Set sizes:
        if (x_max == -1) x_max = ((IplImage*)img)->width - 1;
        if (y_max == -1) y_max = ((IplImage*)img)->height - 1;

        ASSERT_(x_min >= 0 && x_min < ((IplImage*)img)->width && x_min < x_max);
        ASSERT_(y_min >= 0 && y_min < ((IplImage*)img)->height && y_min < y_max);

        int lx = (x_max - x_min + 1);
        int ly = (y_max - y_min + 1);

        if (doResize || (int)outMatrix.getRowCount() < ly ||
                (int)outMatrix.getColCount() < lx)
                outMatrix.setSize(y_max - y_min + 1, x_max - x_min + 1);

        if (isColor())
        {
                // Luminance: Y = 0.3R + 0.59G + 0.11B
                for (int y = 0; y < ly; y++)
                {
                        unsigned char* pixels = this->get_unsafe(x_min, y_min + y, 0);
                        float aux;
                        for (int x = 0; x < lx; x++)
                        {
                                aux = *pixels++ * 0.3f * (1.0f / 255);
                                aux += *pixels++ * 0.59f * (1.0f / 255);
                                aux += *pixels++ * 0.11f * (1.0f / 255);
                                outMatrix.set_unsafe(y, x, aux);
                        }
                }
        }
        else
        {
                for (int y = 0; y < ly; y++)
                {
                        unsigned char* pixels = this->get_unsafe(x_min, y_min + y, 0);
                        for (int x = 0; x < lx; x++)
                                outMatrix.set_unsafe(y, x, (*pixels++) * (1.0f / 255));
                }
        }

        MRPT_END
#endif
}

/*---------------------------------------------------------------
                                                getAsRGBMatrices
 ---------------------------------------------------------------*/
void CImage::getAsRGBMatrices(
        mrpt::math::CMatrixFloat& outMatrixR, mrpt::math::CMatrixFloat& outMatrixG,
        mrpt::math::CMatrixFloat& outMatrixB, bool doResize, int x_min, int y_min,
        int x_max, int y_max) const
{
#if MRPT_HAS_OPENCV
        MRPT_START

        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);

        // Set sizes:
        if (x_max == -1) x_max = ((IplImage*)img)->width - 1;
        if (y_max == -1) y_max = ((IplImage*)img)->height - 1;

        ASSERT_(x_min >= 0 && x_min < ((IplImage*)img)->width && x_min < x_max);
        ASSERT_(y_min >= 0 && y_min < ((IplImage*)img)->height && y_min < y_max);

        int lx = (x_max - x_min + 1);
        int ly = (y_max - y_min + 1);

        if (doResize || (int)outMatrixR.getRowCount() < ly ||
                (int)outMatrixR.getColCount() < lx)
                outMatrixR.setSize(y_max - y_min + 1, x_max - x_min + 1);
        if (doResize || (int)outMatrixG.getRowCount() < ly ||
                (int)outMatrixG.getColCount() < lx)
                outMatrixG.setSize(y_max - y_min + 1, x_max - x_min + 1);
        if (doResize || (int)outMatrixB.getRowCount() < ly ||
                (int)outMatrixB.getColCount() < lx)
                outMatrixB.setSize(y_max - y_min + 1, x_max - x_min + 1);

        if (isColor())
        {
                for (int y = 0; y < ly; y++)
                {
                        unsigned char* pixels = this->get_unsafe(x_min, y_min + y, 0);
                        float aux;
                        for (int x = 0; x < lx; x++)
                        {
                                aux = *pixels++ * (1.0f / 255);
                                outMatrixR.set_unsafe(y, x, aux);
                                aux = *pixels++ * (1.0f / 255);
                                outMatrixG.set_unsafe(y, x, aux);
                                aux = *pixels++ * (1.0f / 255);
                                outMatrixB.set_unsafe(y, x, aux);
                        }
                }
        }
        else
        {
                for (int y = 0; y < ly; y++)
                {
                        unsigned char* pixels = this->get_unsafe(x_min, y_min + y, 0);
                        for (int x = 0; x < lx; x++)
                        {
                                outMatrixR.set_unsafe(y, x, (*pixels) * (1.0f / 255));
                                outMatrixG.set_unsafe(y, x, (*pixels) * (1.0f / 255));
                                outMatrixB.set_unsafe(y, x, (*pixels++) * (1.0f / 255));
                        }
                }
        }

        MRPT_END
#endif
}

/*---------------------------------------------------------------
                                                cross_correlation_FFT
 ---------------------------------------------------------------*/
void CImage::cross_correlation_FFT(
        const CImage& in_img, CMatrixFloat& out_corr, int u_search_ini,
        int v_search_ini, int u_search_size, int v_search_size, float biasThisImg,
        float biasInImg) const
{
        MRPT_START

        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);

        // Set limits:
        if (u_search_ini == -1) u_search_ini = 0;
        if (v_search_ini == -1) v_search_ini = 0;
        if (u_search_size == -1) u_search_size = getWidth();
        if (v_search_size == -1) v_search_size = getHeight();

        int u_search_end = u_search_ini + u_search_size - 1;
        int v_search_end = v_search_ini + v_search_size - 1;

        ASSERT_(u_search_end < (int)getWidth());
        ASSERT_(v_search_end < (int)getHeight());

        // Find smallest valid size:
        size_t x, y;
        size_t actual_lx = max(u_search_size, (int)in_img.getWidth());
        size_t actual_ly = max(v_search_size, (int)in_img.getHeight());
        size_t lx = math::round2up(actual_lx);
        size_t ly = math::round2up(actual_ly);

        //      printf("ly=%u lx=%u\n",ly,lx);

        CMatrix i1(ly, lx), i2(ly, lx);

        // We fill the images with the bias, such as when we substract the bias
        // later on,
        //  those pixels not really occupied by the image really becomes zero:
        i1.fill(biasInImg);
        i2.fill(biasThisImg);

        // Get as matrixes, padded with zeros up to power-of-two sizes:
        getAsMatrix(
                i2, false, u_search_ini, v_search_ini, u_search_ini + u_search_size - 1,
                v_search_ini + v_search_size - 1);
        in_img.getAsMatrix(i1, false);

        // Remove the bias now:
        i2.array() -= biasThisImg;
        i1.array() -= biasInImg;

        // Fill the "padded zeros" with copies of the images:
        //      SAVE_MATRIX(i1); SAVE_MATRIX(i2);

        // FFT:
        CMatrix I1_R, I1_I, I2_R, I2_I, ZEROS(ly, lx);
        math::dft2_complex(i1, ZEROS, I1_R, I1_I);
        math::dft2_complex(i2, ZEROS, I2_R, I2_I);

        //      SAVE_MATRIX(I1_R); SAVE_MATRIX(I1_I);
        //      SAVE_MATRIX(I2_R); SAVE_MATRIX(I2_I);

        // Compute the COMPLEX division of I2 by I1:
        for (y = 0; y < ly; y++)
                for (x = 0; x < lx; x++)
                {
                        float r1 = I1_R.get_unsafe(y, x);
                        float r2 = I2_R.get_unsafe(y, x);

                        float ii1 = I1_I.get_unsafe(y, x);
                        float ii2 = I2_I.get_unsafe(y, x);

                        float den = square(r1) + square(ii1);
                        I2_R.set_unsafe(y, x, (r1 * r2 + ii1 * ii2) / den);
                        I2_I.set_unsafe(y, x, (ii2 * r1 - r2 * ii1) / den);
                }

        //      I2_R.saveToTextFile("DIV_R.txt");
        //      I2_I.saveToTextFile("DIV_I.txt");

        // IFFT:
        CMatrix res_R, res_I;
        math::idft2_complex(I2_R, I2_I, res_R, res_I);

        out_corr.setSize(actual_ly, actual_lx);
        for (y = 0; y < actual_ly; y++)
                for (x = 0; x < actual_lx; x++)
                        out_corr(y, x) = sqrt(square(res_R(y, x)) + square(res_I(y, x)));

        MRPT_END
}

/*---------------------------------------------------------------
                                                getAsMatrixTiled
 ---------------------------------------------------------------*/
void CImage::getAsMatrixTiled(CMatrix& outMatrix) const
{
#if MRPT_HAS_OPENCV
        MRPT_START

        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);

        // The size of the matrix:
        size_t matrix_lx = outMatrix.getColCount();
        size_t matrix_ly = outMatrix.getRowCount();

        if (isColor())
        {
                // Luminance: Y = 0.3R + 0.59G + 0.11B
                for (unsigned int y = 0; y < matrix_ly; y++)
                {
                        unsigned char* min_pixels =
                                (*this)(0, y % ((IplImage*)img)->height, 0);
                        unsigned char* max_pixels =
                                min_pixels + ((IplImage*)img)->width * 3;
                        unsigned char* pixels = min_pixels;
                        float aux;
                        for (unsigned int x = 0; x < matrix_lx; x++)
                        {
                                aux = *pixels++ * 0.30f;
                                aux += *pixels++ * 0.59f;
                                aux += *pixels++ * 0.11f;
                                outMatrix.set_unsafe(y, x, aux);
                                if (pixels >= max_pixels) pixels = min_pixels;
                        }
                }
        }
        else
        {
                for (unsigned int y = 0; y < matrix_ly; y++)
                {
                        unsigned char* min_pixels =
                                (*this)(0, y % ((IplImage*)img)->height, 0);
                        unsigned char* max_pixels = min_pixels + ((IplImage*)img)->width;
                        unsigned char* pixels = min_pixels;
                        for (unsigned int x = 0; x < matrix_lx; x++)
                        {
                                outMatrix.set_unsafe(y, x, *pixels++);
                                if (pixels >= max_pixels) pixels = min_pixels;
                        }
                }
        }

        MRPT_END
#endif
}

/*---------------------------------------------------------------
                                                setExternalStorage
 ---------------------------------------------------------------*/
void CImage::setExternalStorage(const std::string& fileName) noexcept
{
        releaseIpl();
        m_externalFile = fileName;
        m_imgIsExternalStorage = true;
}

/*---------------------------------------------------------------
                                                unload
 ---------------------------------------------------------------*/
void CImage::unload() const noexcept
{
        if (m_imgIsExternalStorage)
                const_cast<CImage*>(this)->releaseIpl(
                        true);  // Do NOT mark the image as NON external
}

/*---------------------------------------------------------------
                                                releaseIpl
 ---------------------------------------------------------------*/
void CImage::releaseIpl(bool thisIsExternalImgUnload) noexcept
{
#if MRPT_HAS_OPENCV
        if (img && !m_imgIsReadOnly)
        {
                IplImage* ptr = (IplImage*)img;
                cvReleaseImage(&ptr);
        }
        img = nullptr;
        m_imgIsReadOnly = false;
        if (!thisIsExternalImgUnload)
        {
                m_imgIsExternalStorage = false;
                m_externalFile = string();
        }
#endif
}

/*---------------------------------------------------------------
                                makeSureImageIsLoaded
 ---------------------------------------------------------------*/
void CImage::makeSureImageIsLoaded() const
{
        if (img != nullptr) return;  // OK, continue

        if (m_imgIsExternalStorage)
        {
                // Load the file:
                string wholeFile;
                getExternalStorageFileAbsolutePath(wholeFile);

                const std::string tmpFile = m_externalFile;

                bool ret = const_cast<CImage*>(this)->loadFromFile(wholeFile);

                // These are removed by "loadFromFile", and that's good, just fix it
                // here and carry on.
                m_imgIsExternalStorage = true;
                m_externalFile = tmpFile;

                if (!ret)
                        THROW_TYPED_EXCEPTION_FMT(
                                CExceptionExternalImageNotFound,
                                "Error loading externally-stored image from: %s",
                                wholeFile.c_str());
        }
        else
                THROW_EXCEPTION("img is nullptr in a non-externally stored image.");
}

/*---------------------------------------------------------------
                                getExternalStorageFileAbsolutePath
 ---------------------------------------------------------------*/
void CImage::getExternalStorageFileAbsolutePath(std::string& out_path) const
{
        ASSERT_(m_externalFile.size() > 2);

        if (m_externalFile[0] == '/' ||
                (m_externalFile[1] == ':' && m_externalFile[2] == '\\'))
        {
                out_path = m_externalFile;
        }
        else
        {
                out_path = IMAGES_PATH_BASE;

                size_t N = IMAGES_PATH_BASE.size() - 1;
                if (IMAGES_PATH_BASE[N] != '/' && IMAGES_PATH_BASE[N] != '\\')
                        out_path += "/";

                out_path += m_externalFile;
        }
}

/*---------------------------------------------------------------
                                flipVertical
 ---------------------------------------------------------------*/
void CImage::flipVertical(bool also_swapRB)
{
#if MRPT_HAS_OPENCV
        IplImage* ptr = (IplImage*)img;
        int options = CV_CVTIMG_FLIP;
        if (also_swapRB) options |= CV_CVTIMG_SWAP_RB;
        cvConvertImage(ptr, ptr, options);
#endif
}

void CImage::flipHorizontal()
{
#if MRPT_HAS_OPENCV
        IplImage* ptr = (IplImage*)img;
        cvFlip(ptr, nullptr, 1);
#endif
}

/*---------------------------------------------------------------
                                swapRB
 ---------------------------------------------------------------*/
void CImage::swapRB()
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        IplImage* ptr = (IplImage*)img;
        cvConvertImage(ptr, ptr, CV_CVTIMG_SWAP_RB);
#endif
}

/*---------------------------------------------------------------
                                        rectifyImageInPlace
 ---------------------------------------------------------------*/
void CImage::rectifyImageInPlace(void* mapX, void* mapY)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);

#if MRPT_OPENCV_VERSION_NUM < 0x200
        THROW_EXCEPTION("This method requires OpenCV 2.0.0 or above.")
#else

        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg =
                cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        cv::Mat *_mapX, *_mapY;
        _mapX = static_cast<cv::Mat*>(mapX);
        _mapY = static_cast<cv::Mat*>(mapY);

        IplImage _mapXX = *_mapX;
        IplImage _mapYY = *_mapY;

        cvRemap(srcImg, outImg, &_mapXX, &_mapYY, CV_INTER_CUBIC);
#endif

        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                        rectifyImageInPlace
 ---------------------------------------------------------------*/
void CImage::rectifyImageInPlace(const mrpt::utils::TCamera& cameraParams)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        double aux1[3][3], aux2[1][5];
        const CMatrixDouble33& cameraMatrix = cameraParams.intrinsicParams;

        for (int i = 0; i < 3; i++)
                for (int j = 0; j < 3; j++) aux1[i][j] = cameraMatrix(i, j);
        for (int i = 0; i < 5; i++) aux2[0][i] = cameraParams.dist[i];

        CvMat inMat = cvMat(
                cameraMatrix.getRowCount(), cameraMatrix.getColCount(), CV_64F, aux1);
        CvMat distM = cvMat(1, 5, CV_64F, aux2);

        // Remove distortion
        cvUndistort2(srcImg, outImg, &inMat, &distM);

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                                rectifyImage
 ---------------------------------------------------------------*/
void CImage::rectifyImage(
        CImage& out_img, const mrpt::utils::TCamera& cameraParams) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        const IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        double aux1[3][3], aux2[1][5];
        const CMatrixDouble33& cameraMatrix = cameraParams.intrinsicParams;

        for (int i = 0; i < 3; i++)
                for (int j = 0; j < 3; j++) aux1[i][j] = cameraMatrix(i, j);
        for (int i = 0; i < 5; i++) aux2[0][i] = cameraParams.dist[i];

        CvMat inMat = cvMat(
                cameraMatrix.getRowCount(), cameraMatrix.getColCount(), CV_64F, aux1);
        CvMat distM = cvMat(1, 5, CV_64F, aux2);

        // Remove distortion
        cvUndistort2(srcImg, outImg, &inMat, &distM);

        // OpenCV -> MRPT Output Transformation
        out_img.loadFromIplImage(outImg);

        // Release Output Image
        cvReleaseImage(&outImg);
#endif
}  // end CImage::rectifyImage

/*---------------------------------------------------------------
                                                filterMedian
 ---------------------------------------------------------------*/
void CImage::filterMedian(CImage& out_img, int W) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        const IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        // Filter
        cvSmooth(srcImg, outImg, CV_MEDIAN, W);

        outImg->origin = srcImg->origin;

        // OpenCV -> MRPT Output Transformation
        out_img.loadFromIplImage(outImg);

        // Release Output Image
        cvReleaseImage(&outImg);
#endif
}

/*---------------------------------------------------------------
                                                filterMedian
 ---------------------------------------------------------------*/
void CImage::filterMedianInPlace(int W)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        // Filter
        cvSmooth(srcImg, outImg, CV_MEDIAN, W);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                                filterGaussian
 ---------------------------------------------------------------*/
void CImage::filterGaussian(CImage& out_img, int W, int H) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        const IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        // Filter
        cvSmooth(srcImg, outImg, CV_GAUSSIAN, W, H);

        outImg->origin = srcImg->origin;

        // OpenCV -> MRPT Output Transformation
        out_img.loadFromIplImage(outImg);

        // Release Output Image
        cvReleaseImage(&outImg);
#endif
}

/*---------------------------------------------------------------
                                                filterGaussianInPlace
 ---------------------------------------------------------------*/
void CImage::filterGaussianInPlace(int W, int H)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        // MRPT -> OpenCV Input Transformation
        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        // Filter
        cvSmooth(srcImg, outImg, CV_GAUSSIAN, W, H);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                                scaleImage
 ---------------------------------------------------------------*/
void CImage::scaleImage(
        unsigned int width, unsigned int height, TInterpolationMethod interp)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        IplImage* srcImg = getAs<IplImage>();  // Source Image

        if (static_cast<unsigned int>(srcImg->width) == width &&
                static_cast<unsigned int>(srcImg->height) == height)
                return;

        IplImage* outImg;  // Output Image
        outImg =
                cvCreateImage(cvSize(width, height), srcImg->depth, srcImg->nChannels);

        // Resize:
        cvResize(srcImg, outImg, (int)interp);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                                scaleImage
 ---------------------------------------------------------------*/
void CImage::scaleImage(
        CImage& out_img, unsigned int width, unsigned int height,
        TInterpolationMethod interp) const
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);
        const IplImage* srcImg = getAs<IplImage>();  // Source Image

        if (static_cast<unsigned int>(srcImg->width) == width &&
                static_cast<unsigned int>(srcImg->height) == height)
        {
                // already at the required size:
                out_img = *this;
                return;
        }

        IplImage* outImg;  // Output Image
        outImg =
                cvCreateImage(cvSize(width, height), srcImg->depth, srcImg->nChannels);

        // Resize:
        cvResize(srcImg, outImg, (int)interp);
        outImg->origin = srcImg->origin;

        // Assign:
        out_img.setFromIplImage(outImg);
#endif
}

/*---------------------------------------------------------------
                                                rotateImage
 ---------------------------------------------------------------*/
void CImage::rotateImage(
        double angle_radians, unsigned int center_x, unsigned int center_y,
        double scale)
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img != nullptr);

        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);

        // Based on the blog entry:
        // http://blog.weisu.org/2007/12/opencv-image-rotate-and-zoom-rotation.html

        // Apply rotation & scale:
        float m[6];
        CvMat M = cvMat(2, 3, CV_32F, m);

        m[0] = (float)(scale * cos(angle_radians));
        m[1] = (float)(scale * sin(angle_radians));
        m[3] = -m[1];
        m[4] = m[0];
        m[2] = center_x;
        m[5] = center_y;

        cvGetQuadrangleSubPix(srcImg, outImg, &M);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;

#endif
}

/** Draw onto this image the detected corners of a chessboard. The length of
* cornerCoords must be the product of the two check_sizes.
*
* \param cornerCoords [IN] The pixel coordinates of all the corners.
* \param check_size_x [IN] The number of squares, in the X direction
* \param check_size_y [IN] The number of squares, in the Y direction
*
* \return false if the length of cornerCoords is inconsistent (nothing is drawn
* then).
*/
bool CImage::drawChessboardCorners(
        std::vector<TPixelCoordf>& cornerCoords, unsigned int check_size_x,
        unsigned int check_size_y, unsigned int lines_width, unsigned int r)
{
#if MRPT_HAS_OPENCV

        if (cornerCoords.size() != check_size_x * check_size_y) return false;

        IplImage* ipl = this->getAs<IplImage>();

        unsigned int x, y, i;
        CvPoint prev_pt = cvPoint(0, 0);
        const int line_max = 8;
        CvScalar line_colors[8];

        line_colors[0] = CV_RGB(255, 0, 0);
        line_colors[1] = CV_RGB(255, 128, 0);
        line_colors[2] = CV_RGB(255, 128, 0);
        line_colors[3] = CV_RGB(200, 200, 0);
        line_colors[4] = CV_RGB(0, 255, 0);
        line_colors[5] = CV_RGB(0, 200, 200);
        line_colors[6] = CV_RGB(0, 0, 255);
        line_colors[7] = CV_RGB(255, 0, 255);

        CCanvas::selectTextFont("10x20");

        for (y = 0, i = 0; y < check_size_y; y++)
        {
                CvScalar color = line_colors[y % line_max];
                for (x = 0; x < check_size_x; x++, i++)
                {
                        CvPoint pt;
                        pt.x = cvRound(cornerCoords[i].x);
                        pt.y = cvRound(cornerCoords[i].y);

                        if (i != 0) cvLine(ipl, prev_pt, pt, color, lines_width);

                        cvLine(
                                ipl, cvPoint(pt.x - r, pt.y - r), cvPoint(pt.x + r, pt.y + r),
                                color, lines_width);
                        cvLine(
                                ipl, cvPoint(pt.x - r, pt.y + r), cvPoint(pt.x + r, pt.y - r),
                                color, lines_width);

                        if (r > 0) cvCircle(ipl, pt, r + 1, color);
                        prev_pt = pt;

                        // Text label with the corner index in the first and last corners:
                        if (i == 0 || i == cornerCoords.size() - 1)
                                CCanvas::textOut(
                                        pt.x + 5, pt.y - 5, mrpt::format("%u", i),
                                        mrpt::utils::TColor::blue());
                }
        }

        return true;
#else
        return false;
#endif
}

/** Replaces this grayscale image with a RGB version of it.
  * \sa grayscaleInPlace
  */
void CImage::colorImage(CImage& ret) const
{
#if MRPT_HAS_OPENCV
        if (this->isColor())
        {
                ret = *this;
                return;
        }

        const IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, 3);

        cvCvtColor(srcImg, outImg, CV_GRAY2BGR);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        ret.setFromIplImage(outImg);
#endif
}

/** Replaces this grayscale image with a RGB version of it.
  * \sa grayscaleInPlace
  */
void CImage::colorImageInPlace()
{
#if MRPT_HAS_OPENCV
        if (this->isColor()) return;

        IplImage* srcImg = getAs<IplImage>();  // Source Image
        IplImage* outImg;  // Output Image
        outImg = cvCreateImage(cvGetSize(srcImg), srcImg->depth, 3);

        cvCvtColor(srcImg, outImg, CV_GRAY2BGR);

        outImg->origin = srcImg->origin;

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;
#endif
}

/*---------------------------------------------------------------
                                                joinImagesHorz
 ---------------------------------------------------------------*/
void CImage::joinImagesHorz(const CImage& im1, const CImage& im2)
{
#if MRPT_HAS_OPENCV
        ASSERT_(im1.getHeight() == im2.getHeight());

        const IplImage* _im1 = im1.getAs<IplImage>();
        const IplImage* _im2 = im2.getAs<IplImage>();

        ASSERT_(_im1->depth == _im2->depth && _im1->nChannels == _im2->nChannels);

        IplImage* out = cvCreateImage(
                cvSize(_im1->width + _im2->width, _im1->height), _im1->depth,
                _im1->nChannels);

        cvSetImageROI(out, cvRect(0, 0, _im1->width, _im1->height));
        cvCopy(_im1, out);
        cvSetImageROI(out, cvRect(_im1->width, 0, _im2->width, _im2->height));
        cvCopy(_im2, out);
        cvSetImageROI(out, cvRect(0, 0, out->width, out->height));

        IplImage* out2;
        if ((int)_im1->nChannels != (int)this->getChannelCount())  // Convert the
        // input to the
        // output channel
        // format
        {
                out2 = cvCreateImage(
                        cvSize(_im1->width + _im2->width, _im1->height), _im1->depth,
                        this->getChannelCount());
                cvCvtColor(out, out2, CV_GRAY2BGR);
                this->setFromIplImageReadOnly(out2);
        }
        else  // Assign the output image to the IPLImage pointer within the CImage
                this->setFromIplImageReadOnly(out);

#endif
}  // end

/*---------------------------------------------------------------
                                                equalizeHist
 ---------------------------------------------------------------*/
void CImage::equalizeHist(CImage& outImg) const
{
#if MRPT_HAS_OPENCV
        // Convert to a single luminance channel image
        const IplImage* srcImg = getAs<IplImage>();  // Source Image
        ASSERT_(srcImg != nullptr)

        outImg.changeSize(srcImg->width, srcImg->height, 1, isOriginTopLeft());

        if (srcImg->nChannels == 1)
        {  // Grayscale:
                cvEqualizeHist(srcImg, outImg.getAs<IplImage>());
        }
        else
        {  // Color:
                IplImage* hsv = cvCreateImage(cvGetSize(srcImg), 8, 3);
                IplImage* h = cvCreateImage(cvGetSize(srcImg), 8, 1);
                IplImage* s = cvCreateImage(cvGetSize(srcImg), 8, 1);
                IplImage* v = cvCreateImage(cvGetSize(srcImg), 8, 1);

                cvCvtColor(srcImg, hsv, CV_BGR2HSV);
                cvSplit(hsv, h, s, v, nullptr);

                cvEqualizeHist(v, v);

                cvMerge(h, s, v, nullptr, hsv);
                cvCvtColor(hsv, outImg.getAs<IplImage>(), CV_HSV2BGR);

                cvReleaseImage(&hsv);
                cvReleaseImage(&h);
                cvReleaseImage(&s);
                cvReleaseImage(&v);
        }

#endif
}

/*---------------------------------------------------------------
                                                equalizeHistInPlace
 ---------------------------------------------------------------*/
void CImage::equalizeHistInPlace()
{
#if MRPT_HAS_OPENCV
        // Convert to a single luminance channel image
        IplImage* srcImg = getAs<IplImage>();  // Source Image
        ASSERT_(srcImg != nullptr);

        IplImage* outImg =
                cvCreateImage(cvGetSize(srcImg), srcImg->depth, srcImg->nChannels);
        outImg->origin = srcImg->origin;

        if (srcImg->nChannels == 1)
        {  // Grayscale:
                cvEqualizeHist(srcImg, outImg);
        }
        else
        {  // Color:
                IplImage* hsv = cvCreateImage(cvGetSize(srcImg), 8, 3);
                IplImage* h = cvCreateImage(cvGetSize(srcImg), 8, 1);
                IplImage* s = cvCreateImage(cvGetSize(srcImg), 8, 1);
                IplImage* v = cvCreateImage(cvGetSize(srcImg), 8, 1);

                cvCvtColor(srcImg, hsv, CV_BGR2HSV);
                cvSplit(hsv, h, s, v, nullptr);

                cvEqualizeHist(v, v);

                cvMerge(h, s, v, nullptr, hsv);
                cvCvtColor(hsv, outImg, CV_HSV2BGR);

                cvReleaseImage(&hsv);
                cvReleaseImage(&h);
                cvReleaseImage(&s);
                cvReleaseImage(&v);
        }

        // Assign the output image to the IPLImage pointer within the CImage
        releaseIpl();
        img = outImg;

#endif
}

template <unsigned int HALF_WIN_SIZE>
void image_KLT_response_template(
        const uint8_t* in, const int widthStep, int x, int y, int32_t& _gxx,
        int32_t& _gyy, int32_t& _gxy)
{
        const unsigned int min_x = x - HALF_WIN_SIZE;
        const unsigned int min_y = y - HALF_WIN_SIZE;

        int32_t gxx = 0;
        int32_t gxy = 0;
        int32_t gyy = 0;

        const unsigned int WIN_SIZE = 1 + 2 * HALF_WIN_SIZE;

        unsigned int yy = min_y;
        for (unsigned int iy = WIN_SIZE; iy; --iy, ++yy)
        {
                const uint8_t* ptr = in + widthStep * yy + min_x;
                unsigned int xx = min_x;
                for (unsigned int ix = WIN_SIZE; ix; --ix, ++xx)
                {
                        const int32_t dx = ptr[+1] - ptr[-1];
                        const int32_t dy = ptr[+widthStep] - ptr[-widthStep];
                        gxx += dx * dx;
                        gxy += dx * dy;
                        gyy += dy * dy;
                }
        }
        _gxx = gxx;
        _gyy = gyy;
        _gxy = gxy;
}

float CImage::KLT_response(
        const unsigned int x, const unsigned int y,
        const unsigned int half_window_size) const
{
#if MRPT_HAS_OPENCV
        const IplImage* srcImg = this->getAs<IplImage>();
        ASSERT_(srcImg != nullptr)
        ASSERTMSG_(
                srcImg->nChannels == 1,
                "KLT_response only works with grayscale images.")

        const unsigned int img_w = srcImg->width;
        const unsigned int img_h = srcImg->height;
        const int widthStep = srcImg->widthStep;

        // If any of those predefined values worked, do the generic way:
        const unsigned int min_x = x - half_window_size;
        const unsigned int max_x = x + half_window_size;
        const unsigned int min_y = y - half_window_size;
        const unsigned int max_y = y + half_window_size;

        // Since min_* are "unsigned", checking "<" will detect negative numbers:
        ASSERTMSG_(
                min_x < img_w && max_x < img_w && min_y < img_h && max_y < img_h,
                "Window is out of image bounds")

        // Gradient sums: Use integers since they're much faster than
        // doubles/floats!!
        int32_t gxx = 0;
        int32_t gxy = 0;
        int32_t gyy = 0;

        const uint8_t* img_data = reinterpret_cast<const uint8_t*>(
                srcImg->imageData);  //*VERY IMPORTANT*: Use unsigned
        switch (half_window_size)
        {
                case 2:
                        image_KLT_response_template<2>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 3:
                        image_KLT_response_template<3>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 4:
                        image_KLT_response_template<4>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 5:
                        image_KLT_response_template<5>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 6:
                        image_KLT_response_template<6>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 7:
                        image_KLT_response_template<7>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 8:
                        image_KLT_response_template<8>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 9:
                        image_KLT_response_template<9>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 10:
                        image_KLT_response_template<10>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 11:
                        image_KLT_response_template<11>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 12:
                        image_KLT_response_template<12>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 13:
                        image_KLT_response_template<13>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 14:
                        image_KLT_response_template<14>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 15:
                        image_KLT_response_template<15>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 16:
                        image_KLT_response_template<16>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;
                case 32:
                        image_KLT_response_template<32>(
                                img_data, widthStep, x, y, gxx, gyy, gxy);
                        break;

                default:
                        for (unsigned int yy = min_y; yy <= max_y; yy++)
                        {
                                const uint8_t* ptr = img_data + widthStep * yy + min_x;
                                for (unsigned int xx = min_x; xx <= max_x; xx++)
                                {
                                        const int32_t dx = ptr[+1] - ptr[-1];
                                        const int32_t dy = ptr[+widthStep] - ptr[-widthStep];
                                        gxx += dx * dx;
                                        gxy += dx * dy;
                                        gyy += dy * dy;
                                }
                        }
                        break;
        }
        // Convert to float's and normalize in the way:
        const float K = 0.5f / ((max_y - min_y + 1) * (max_x - min_x + 1));
        const float Gxx = gxx * K;
        const float Gxy = gxy * K;
        const float Gyy = gyy * K;

        // Return the minimum eigenvalue of:
        //    ( gxx  gxy )
        //    ( gxy  gyy )
        // See, for example: mrpt::math::detail::eigenVectorsMatrix_special_2x2():
        const float t = Gxx + Gyy;  // Trace
        const float de = Gxx * Gyy - Gxy * Gxy;  // Det
        // The smallest eigenvalue is:
        return 0.5f * (t - std::sqrt(t * t - 4.0f * de));
#else
        return 0;
#endif
}

/** Marks the channel ordering in a color image (this doesn't actually modify
 * the image data, just the format description)
  */
void CImage::setChannelsOrder_RGB()
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);
        strcpy(((IplImage*)img)->channelSeq, "RGB");
#else
        THROW_EXCEPTION("MRPT compiled without OpenCV")
#endif
}

void CImage::setChannelsOrder_BGR()
{
#if MRPT_HAS_OPENCV
        makeSureImageIsLoaded();  // For delayed loaded images stored externally
        ASSERT_(img);
        strcpy(((IplImage*)img)->channelSeq, "BGR");
#else
        THROW_EXCEPTION("MRPT compiled without OpenCV")
#endif
}

/** Loads the image from an XPM array, as #include'd from a ".xpm" file.
  * \sa loadFromFile
  * \return false on any error */
bool CImage::loadFromXPM(const char** xpm_array, bool swap_rb)
{
#if MRPT_HAS_OPENCV && MRPT_HAS_WXWIDGETS
        try
        {
                const wxImage b(xpm_array);

                const size_t lx = b.GetWidth();
                const size_t ly = b.GetHeight();

                this->loadFromMemoryBuffer(lx, ly, true, b.GetData(), swap_rb);
                return true;
        }
        catch (std::exception& e)
        {
                std::cerr << "[CImage::loadFromXPM] " << e.what() << std::endl;
                return false;
        }
#else
        MRPT_UNUSED_PARAM(xpm_array);
        MRPT_UNUSED_PARAM(swap_rb);
        return false;
#endif  // MRPT_HAS_OPENCV && MRPT_HAS_WXWIDGETS
}

// Load from TGA files. Used in loadFromFile()
// Contains code from
// https://github.com/tjohnman/Simple-Targa-Library/blob/master/src/simpleTGA.cpp
// (FreeBSD license)
bool CImage::loadTGA(
        const std::string& fileName, mrpt::utils::CImage& out_RGB,
        mrpt::utils::CImage& out_alpha)
{
#if MRPT_HAS_OPENCV
        std::fstream stream;
        stream.open(fileName.c_str(), std::fstream::in | std::fstream::binary);
        if (!stream.is_open())
        {
                std::cerr << "[CImage::loadTGA] Couldn't open file '" << fileName
                                  << "'.\n";
                return false;
        }

        stream.seekg(0, std::ios_base::end);
        // long length = stream.tellg();
        stream.seekg(0, std::ios_base::beg);

        // Simple uncompressed true-color image
        char dumpBuffer[12];
        char trueColorHeader[] = "\0\0\2\0\0\0\0\0\0\0\0\0";
        stream.read(dumpBuffer, 12);
        if (memcmp(dumpBuffer, trueColorHeader, 12) != 0)
        {
                std::cerr << "[CImage::loadTGA] Unsupported format or invalid file.\n";
                return false;
        }

        unsigned short width, height;
        unsigned char bpp;

        stream.read((char*)&width, 2);
        stream.read((char*)&height, 2);
        bpp = stream.get();
        if (bpp != 32)
        {
                std::cerr << "[CImage::loadTGA] Only 32 bpp format supported!\n";
                return false;
        }

        unsigned char desc;
        desc = stream.get();
        if (desc != 8 && desc != 32)
        {
                std::cerr << "[CImage::loadTGA] Unsupported format or invalid file.\n";
                return false;
        }
        const bool origin_is_low_corner = (desc == 8);

        // Data section
        std::vector<uint8_t> bytes(width * height * 4);
        stream.read((char*)&bytes[0], width * height * 4);
        stream.close();

        // Move data to images:
        out_RGB.resize(width, height, CH_RGB, true);
        out_alpha.resize(width, height, CH_GRAY, true);

        size_t idx = 0;
        for (unsigned int r = 0; r < height; r++)
        {
                unsigned int actual_row = origin_is_low_corner ? (height - 1 - r) : r;
                IplImage* ipl = ((IplImage*)out_RGB.img);
                unsigned char* data =
                        (unsigned char*)&ipl->imageData[actual_row * ipl->widthStep];

                IplImage* ipl_alpha = ((IplImage*)out_alpha.img);
                unsigned char* data_alpha =
                        (unsigned char*)&ipl->imageData[actual_row * ipl_alpha->widthStep];

                for (unsigned int c = 0; c < width; c++)
                {
                        *data++ = bytes[idx++];  // R
                        *data++ = bytes[idx++];  // G
                        *data++ = bytes[idx++];  // B
                        *data_alpha++ = bytes[idx++];  // A
                }
        }

        return true;
#else
        return false;
#endif  // MRPT_HAS_OPENCV
}