CImage.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2019, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

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

#include <mrpt/core/round.h>  // for round()
#include <mrpt/img/CImage.h>
#include <mrpt/io/CFileInputStream.h>
#include <mrpt/io/CFileOutputStream.h>
#include <mrpt/io/CMemoryStream.h>
#include <mrpt/io/zip.h>
#include <mrpt/math/CMatrixF.h>
#include <mrpt/math/fourier.h>
#include <mrpt/math/utils.h>  // for roundup()
#include <mrpt/serialization/CArchive.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/CTimeLogger.h>
#include <mrpt/system/filesystem.h>
#include <mrpt/system/memory.h>
#include <iostream>

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

#include "CImage_impl.h"

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

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

using namespace mrpt;
using namespace mrpt::img;
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::img)

static bool DISABLE_ZIP_COMPRESSION_value = false;
static bool DISABLE_JPEG_COMPRESSION_value = true;
static int SERIALIZATION_JPEG_QUALITY_value = 95;
static std::string IMAGES_PATH_BASE(".");

void CImage::DISABLE_ZIP_COMPRESSION(bool val)
{
    DISABLE_ZIP_COMPRESSION_value = val;
}
bool CImage::DISABLE_ZIP_COMPRESSION() { return DISABLE_ZIP_COMPRESSION_value; }
void CImage::DISABLE_JPEG_COMPRESSION(bool val)
{
    DISABLE_JPEG_COMPRESSION_value = val;
}
bool CImage::DISABLE_JPEG_COMPRESSION()
{
    return DISABLE_JPEG_COMPRESSION_value;
}
void CImage::SERIALIZATION_JPEG_QUALITY(int q)
{
    SERIALIZATION_JPEG_QUALITY_value = q;
}
int CImage::SERIALIZATION_JPEG_QUALITY()
{
    return SERIALIZATION_JPEG_QUALITY_value;
}

CExceptionExternalImageNotFound::CExceptionExternalImageNotFound(
    const std::string& s)
    : std::runtime_error(s)
{
}

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::img::CTimeLogger alloc_tims;
#endif

#if MRPT_HAS_OPENCV
static int interpolationMethod2Cv(TInterpolationMethod i)
{
    // clang-format off
    switch (i)
    {
        case IMG_INTERP_NN:     return cv::INTER_NEAREST;
        case IMG_INTERP_LINEAR: return cv::INTER_LINEAR;
        case IMG_INTERP_CUBIC:  return cv::INTER_CUBIC;
        case IMG_INTERP_AREA:   return cv::INTER_AREA;
    };
    // clang-format on
    return -1;
}

template <typename RET = uint32_t>
constexpr RET pixelDepth2CvDepth(PixelDepth d)
{
    // clang-format off
    switch (d)
    {
        case PixelDepth::D8U:  return static_cast<RET>(CV_8U);
        case PixelDepth::D8S:  return static_cast<RET>(CV_8S);
        case PixelDepth::D16U: return static_cast<RET>(CV_16U);
        case PixelDepth::D16S: return static_cast<RET>(CV_16S);
        case PixelDepth::D32S: return static_cast<RET>(CV_32S);
        case PixelDepth::D32F: return static_cast<RET>(CV_32F);
        case PixelDepth::D64F: return static_cast<RET>(CV_64F);
    }
    // clang-format on
    return std::numeric_limits<RET>::max();
}
template <typename RET = uint32_t>
RET pixelDepth2IPLCvDepth(PixelDepth d)
{
    // clang-format off
    switch (d)
    {
        case PixelDepth::D8U:  return static_cast<RET>(IPL_DEPTH_8U);
        case PixelDepth::D8S:  return static_cast<RET>(IPL_DEPTH_8S);
        case PixelDepth::D16U: return static_cast<RET>(IPL_DEPTH_16U);
        case PixelDepth::D16S: return static_cast<RET>(IPL_DEPTH_16S);
        case PixelDepth::D32S: return static_cast<RET>(IPL_DEPTH_32S);
        case PixelDepth::D32F: return static_cast<RET>(IPL_DEPTH_32F);
        case PixelDepth::D64F: return static_cast<RET>(IPL_DEPTH_64F);
    }
    // clang-format on
    return std::numeric_limits<RET>::max();
}

static PixelDepth cvDepth2PixelDepth(int64_t d)
{
    // clang-format off
    switch (d)
    {
        case CV_8U:  return PixelDepth::D8U;
        case CV_8S:  return PixelDepth::D8S;
        case CV_16U: return PixelDepth::D16U;
        case CV_16S: return PixelDepth::D16S;
        case CV_32S: return PixelDepth::D32S;
        case CV_32F: return PixelDepth::D32F;
        case CV_64F: return PixelDepth::D64F;
    }
    // clang-format on
    return PixelDepth::D8U;
}

#endif  // MRPT_HAS_OPENCV

// Default ctor
CImage::CImage() : m_impl(mrpt::make_impl<CImage::Impl>()) {}

// Ctor with size
CImage::CImage(
    unsigned int width, unsigned int height, TImageChannels nChannels)
    : CImage()
{
    MRPT_START
    resize(width, height, nChannels);
    MRPT_END
}

void CImage::swap(CImage& o)
{
    std::swap(m_impl, o.m_impl);
    std::swap(m_imgIsExternalStorage, o.m_imgIsExternalStorage);
    std::swap(m_externalFile, o.m_externalFile);
}

void CImage::copyFromForceLoad(const CImage& o)
{
    *this = o;
    forceLoad();
}

CImage::CImage(const cv::Mat& img, copy_type_t copy_type) : CImage()
{
#if MRPT_HAS_OPENCV
    MRPT_START
    if (copy_type == DEEP_COPY)
        m_impl->img = img.clone();
    else
        m_impl->img = img;
    MRPT_END
#endif
}

CImage::CImage(const CImage& img, copy_type_t copy_type)
    :
#if MRPT_HAS_OPENCV
      CImage(img.m_impl->img, copy_type)
#else
      CImage()
#endif
{
}

CImage CImage::makeDeepCopy() const
{
#if MRPT_HAS_OPENCV
    CImage ret(*this);
    ret.m_impl->img = m_impl->img.clone();
    return ret;
#else
    THROW_EXCEPTION("Operation not supported: build MRPT against OpenCV!");
#endif
}

void CImage::asCvMat(cv::Mat& out_img, copy_type_t copy_type) const
{
#if MRPT_HAS_OPENCV
    if (copy_type == DEEP_COPY)
        out_img = m_impl->img.clone();
    else
        out_img = m_impl->img;
#endif
}

cv::Mat& CImage::asCvMatRef()
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();
    return m_impl->img;
#else
    THROW_EXCEPTION("Operation not supported: build MRPT against OpenCV!");
#endif
}

const cv::Mat& CImage::asCvMatRef() const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();
    return m_impl->img;
#else
    THROW_EXCEPTION("Operation not supported: build MRPT against OpenCV!");
#endif
}

void CImage::resize(
    std::size_t width, std::size_t height, TImageChannels nChannels,
    PixelDepth depth)
{
    MRPT_START

#if MRPT_HAS_OPENCV
    // Dont call makeSureImageIsLoaded() here,
    // since it will throw if resize() is called from a ctor, where it's
    // legit for the img to be uninitialized.

    // If we're resizing to exactly the current size, do nothing:
    {
        _IplImage ipl = m_impl->img;

        if (static_cast<unsigned>(ipl.width) == width &&
            static_cast<unsigned>(ipl.height) == height &&
            ipl.nChannels == nChannels &&
            static_cast<unsigned>(ipl.depth) == pixelDepth2IPLCvDepth(depth))
        {
            // Nothing to do:
            return;
        }
    }

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

    static_assert(
        pixelDepth2CvDepth<int>(PixelDepth::D8U) + CV_8UC(3) == CV_8UC3);

    m_impl->img = cv::Mat(
        static_cast<int>(height), static_cast<int>(width),
        pixelDepth2CvDepth<int>(depth) + ((nChannels - 1) << CV_CN_SHIFT));

#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
}

PixelDepth CImage::getPixelDepth() const
{
    MRPT_START
#if MRPT_HAS_OPENCV
    return cvDepth2PixelDepth(m_impl->img.depth());
#else
    THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
    MRPT_END
}

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

#if MRPT_HAS_OPENCV
    m_imgIsExternalStorage = false;
#ifdef HAVE_OPENCV_IMGCODECS
    MRPT_TODO("Port to cv::imdecode()?");
    MRPT_TODO("add flag to reuse current img buffer");

    m_impl->img = cv::imread(fileName, static_cast<cv::ImreadModes>(isColor));
#else
    IplImage* newImg = cvLoadImage(fileName.c_str(), isColor);
    if (!newImg) return false;
    m_impl->img = cv::cvarrToMat(newImg);
#endif
    if (m_impl->img.empty()) return false;

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

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_(!m_impl->img.empty());

#ifdef HAVE_OPENCV_IMGCODECS
    const std::vector<int> params = {cv::IMWRITE_JPEG_QUALITY, jpeg_quality};
    return cv::imwrite(fileName, m_impl->img, params);
#else
    int p[3] = {CV_IMWRITE_JPEG_QUALITY, jpeg_quality, 0};
    _IplImage ipl = m_impl->img;
    return (0 != cvSaveImage(fileName.c_str(), &ipl, p));
#endif
#else
    THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
    MRPT_END
}

void CImage::internal_fromIPL(const IplImage* iplImage, copy_type_t c)
{
    MRPT_START
#if MRPT_HAS_OPENCV
    ASSERT_(iplImage != nullptr);
    clear();
    m_impl->img =
        cv::cvarrToMat(iplImage, c == DEEP_COPY ? true : false /*copyData*/);
#else
    THROW_EXCEPTION("The MRPT has been compiled with MRPT_HAS_OPENCV=0 !");
#endif
    MRPT_END
}

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 ? CH_RGB : CH_GRAY);
    m_imgIsExternalStorage = false;

    _IplImage ii(m_impl->img);
    IplImage* img = &ii;

    if (color && swapRedBlue)
    {
        // Do copy & swap at once:
        unsigned char* ptr_src = rawpixels;
        auto* ptr_dest = reinterpret_cast<unsigned char*>(img->imageData);
        const int bytes_per_row_out = 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 (img->widthStep == img->width * img->nChannels)
        {
            // Copy the image data:
            memcpy(img->imageData, rawpixels, img->imageSize);
        }
        else
        {
            // Copy the image row by row:
            unsigned char* ptr_src = rawpixels;
            auto* ptr_dest = reinterpret_cast<unsigned char*>(img->imageData);
            int bytes_per_row = width * (color ? 3 : 1);
            int bytes_per_row_out = 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
}

unsigned char* CImage::operator()(
    unsigned int ucol, unsigned int urow, unsigned int uchannel) const
{
#if MRPT_HAS_OPENCV

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

    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    const auto col = static_cast<int>(ucol);
    const auto row = static_cast<int>(urow);
    const auto channel = static_cast<int>(uchannel);

#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
    ASSERT_(m_impl && !m_impl->img.empty());
    if (row >= m_impl->img.rows || col >= m_impl->img.cols ||
        channel >= m_impl->img.channels())
    {
        THROW_EXCEPTION(format(
            "Pixel coordinates/channel out of bounds: row=%u/%u col=%u/%u "
            "chan=%u/%u",
            row, m_impl->img.rows, col, m_impl->img.cols, channel,
            m_impl->img.channels()));
    }
#endif
    auto p =
        (&m_impl->img.at<uint8_t>(row, m_impl->img.channels() * col)) + channel;
    return const_cast<unsigned char*>(p);
#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
    MRPT_END
#endif

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

uint8_t* CImage::internal_get(int col, int row, uint8_t channel) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    auto p =
        (&m_impl->img.at<uint8_t>(row, m_impl->img.channels() * col)) + channel;
    return const_cast<uint8_t*>(p);
#else
    return nullptr;
#endif
}

uint8_t* CImage::get_unsafe(
    unsigned int col, unsigned int row, uint8_t channel) const
{
    return internal_get(col, row, channel);
}

uint8_t CImage::serializeGetVersion() const
{
#if !MRPT_HAS_OPENCV
    return 100;
#else
    return 9;
#endif
}
void CImage::serializeTo(mrpt::serialization::CArchive& out) const
{
#if !MRPT_HAS_OPENCV
    out << m_imgIsExternalStorage;
    if (m_imgIsExternalStorage) out << m_externalFile;
// Nothing else to serialize!
#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_(m_impl);

            const bool hasColor = m_impl->img.empty() ? false : isColor();

            out << hasColor;

            // Version >2: Color->JPEG, GrayScale->BYTE's array!
            const int32_t width = m_impl->img.cols;
            const int32_t height = m_impl->img.rows;
            if (!hasColor)
            {
                // GRAY-SCALE: Raw bytes:
                // Version 3: ZIP compression!
                // Version 4: Skip zip if the image size <= 16Kb
                int32_t origin = 0;  // not used mrpt v1.9.9
                uint32_t imageSize = height * m_impl->img.step[0];
                // Version 10: depth
                int32_t depth = m_impl->img.depth();

                out << width << height << origin << imageSize
                    << int32_t(cvDepth2PixelDepth(depth));

                // 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;
                    mrpt::io::zip::compress(
                        m_impl->img.data, imageSize, tempBuf);

                    auto zipDataLen = static_cast<int32_t>(tempBuf.size());
                    out << zipDataLen;

                    out.WriteBuffer(&tempBuf[0], tempBuf.size());
                    tempBuf.clear();
                }
                else
                {
                    if (imageSize > 0 && m_impl->img.data != nullptr)
                        out.WriteBuffer(m_impl->img.data, imageSize);
                }
            }
            else
            {
                // COLOR: High quality JPEG image

                // v7: If size is 0xN or Nx0, don't call
                // "saveToStreamAsJPEG"!!

                // 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:
                        mrpt::io::CMemoryStream aux;
                        saveToStreamAsJPEG(
                            aux, CImage::SERIALIZATION_JPEG_QUALITY());

                        const auto 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 auto bytes_per_row = width * 3;

                    out.WriteBuffer(m_impl->img.data, bytes_per_row * height);
                }
            }
        }  // end m_imgIsExternalStorage=false
    }
#endif
}

void CImage::serializeFrom(mrpt::serialization::CArchive& in, uint8_t 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
    // First, free current image.
    clear();

    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;

            resize(width, height, static_cast<TImageChannels>(nChannels));
            in.ReadBuffer(m_impl->img.data, imgLength);
        }
        break;
        case 1:
        {
            // Version 1: High quality JPEG image
            mrpt::io::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:
        case 9:
        {
            // 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;
                    PixelDepth depth(PixelDepth::D8U);
                    if (version >= 9)
                    {
                        int32_t tempdepth;
                        in >> tempdepth;
                        depth = PixelDepth(tempdepth);
                    }
                    resize(
                        static_cast<uint32_t>(width),
                        static_cast<uint32_t>(height), CH_GRAY, depth);
                    ASSERT_(
                        static_cast<uint32_t>(imageSize) ==
                        static_cast<uint32_t>(width) *
                            static_cast<uint32_t>(height) *
                            m_impl->img.step[0]);

                    if (version == 2)
                    {
                        // RAW BYTES:
                        in.ReadBuffer(m_impl->img.data, 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;

#if 0
                        size_t outDataBufferSize = imageSize;
                        size_t outDataActualSize;
                        mrpt::io::zip::decompress(
                            in, zipDataLen, m_impl->img.data,
                            outDataBufferSize, outDataActualSize);
                        ASSERT_(outDataActualSize == outDataBufferSize);
#else
                            THROW_EXCEPTION(
                                "ZIP image deserialization not "
                                "implemented");
#endif
                        }
                        else
                        {
                            // Raw bytes:
                            if (imageSize)
                                in.ReadBuffer(m_impl->img.data, 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;

                                resize(real_w, real_h, CH_RGB);

                                auto& img = m_impl->img;
                                const size_t bytes_per_row = img.cols * 3;
                                for (int y = 0; y < img.rows; y++)
                                {
                                    const size_t nRead = in.ReadBuffer(
                                        img.ptr<void>(y), 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:
                                resize(width, height, CH_RGB);
                            }
                        }
                    }

                    // COLOR IMAGE: JPEG
                    if (loadJPEG)
                    {
                        mrpt::io::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::img::CImage)
#endif

mxArray* CImage::writeToMatlab() const
{
#if MRPT_HAS_MATLAB
    cv::Mat cvImg = cv::cvarrToMat(this->getAs<IplImage>());
    return mexplus::from(cvImg);
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

void CImage::getSize(TImageSize& s) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    s.x = m_impl->img.cols;
    s.y = m_impl->img.rows;
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

size_t CImage::getWidth() const
{
#if MRPT_HAS_OPENCV
    if (m_imgIsExternalStorage) makeSureImageIsLoaded();
    return m_impl->img.cols;
#else
    return 0;
#endif
}

std::string CImage::getChannelsOrder() const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    IplImage ipl(m_impl->img);
    return std::string(ipl.channelSeq);
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

size_t CImage::getRowStride() const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    return m_impl->img.step[0];
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

size_t CImage::getHeight() const
{
#if MRPT_HAS_OPENCV
    if (m_imgIsExternalStorage) makeSureImageIsLoaded();
    return m_impl->img.rows;
#else
    return 0;
#endif
}

bool CImage::isColor() const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    return m_impl->img.channels() == 3;
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

TImageChannels CImage::getChannelCount() const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    return static_cast<TImageChannels>(m_impl->img.channels());
#else
    THROW_EXCEPTION("MRPT built without MATLAB/Mex support");
#endif
}

bool CImage::isOriginTopLeft() const
{
    return true;  // As of mrpt v1.9.9
}

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;
}

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;
}

CImage CImage::grayscale() const
{
    CImage ret;
    grayscale(ret);
    return ret;
}

// Auxiliary function for both ::grayscale() and ::grayscaleInPlace()
#if MRPT_HAS_OPENCV
static bool my_img_to_grayscale(const cv::Mat& src, cv::Mat& dest)
{
    if (dest.size() != src.size() || dest.type() != src.type())
        dest = cv::Mat(src.rows, src.cols, CV_8UC1);

// If possible, use SSE optimized version:
#if MRPT_HAS_SSE3
    if ((src.step[0] & 0x0f) == 0 && (dest.step[0] & 0x0f) == 0)
    {
        image_SSSE3_bgr_to_gray_8u(
            src.ptr<uint8_t>(), dest.ptr<uint8_t>(), src.cols, src.rows,
            src.step[0], dest.step[0]);
        return true;
    }
#endif
    // OpenCV Method:
    cv::cvtColor(src, dest, CV_BGR2GRAY);
    return false;
}
#endif

bool CImage::grayscale(CImage& ret) const
{
#if MRPT_HAS_OPENCV
    // The image is already grayscale??
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    if (m_impl->img.channels() == 1)
    {
        ret = *this;  // shallow copy
        return true;
    }
    else
    {
        // Convert to a single luminance channel image
        cv::Mat src = m_impl->img;
        // Detect in-place op and make deep copy:
        if (src.data == ret.m_impl->img.data) src = src.clone();

        return my_img_to_grayscale(src, ret.m_impl->img);
    }
#else
    THROW_EXCEPTION("Operation not supported: build MRPT against OpenCV!");
#endif
}

bool CImage::scaleHalf(CImage& out, TInterpolationMethod interp) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    // Get this image size:
    auto& img = m_impl->img;
    const int w = img.cols, h = img.rows;

    // Create target image:
    out.resize(w >> 1, h >> 1, getChannelCount());
    auto& img_out = out.m_impl->img;

    // If possible, use SSE optimized version:
#if MRPT_HAS_SSE3
    if (img.channels() == 3 && interp == IMG_INTERP_NN)
    {
        image_SSSE3_scale_half_3c8u(
            img.data, img_out.data, w, h, img.step[0], img_out.step[0]);
        return true;
    }
#endif
#if MRPT_HAS_SSE2
    if (img.channels() == 1)
    {
        if (interp == IMG_INTERP_NN)
        {
            image_SSE2_scale_half_1c8u(
                img.data, img_out.data, w, h, img.step[0], img_out.step[0]);
            return true;
        }
        else if (interp == IMG_INTERP_LINEAR)
        {
            image_SSE2_scale_half_smooth_1c8u(
                img.data, img_out.data, w, h, img.step[0], img_out.step[0]);
            return true;
        }
    }
#endif

    // Fall back to slow method:
    cv::resize(
        img, img_out, img_out.size(), 0, 0, interpolationMethod2Cv(interp));
    return false;
#else
    THROW_EXCEPTION("Operation not supported: build MRPT against OpenCV!");
#endif
}

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

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

    resize(width, height, CH_RGB, PixelDepth::D8U);

    // Copy the image data:
    for (unsigned int y = 0; y < height; y++)
    {
        // The target pixels:
        auto* dest = m_impl->img.ptr<uint8_t>(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
}

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
    auto& img = m_impl->img;

    ASSERT_(this->getPixelDepth() == mrpt::img::PixelDepth::D8U);

    if (x >= 0 && y >= 0 && y < img.rows && x < img.cols)
    {
        // The pixel coordinates is valid:
        if (img.channels() == 1)
        {
            img.ptr<uint8_t>(y)[x] = static_cast<uint8_t>(color);
        }
        else
        {
#if defined(_DEBUG) || (MRPT_ALWAYS_CHECKS_DEBUG)
            ASSERT_(img.channels() == 3);
#endif
            auto* dest = &img.ptr<uint8_t>(y)[3 * x];
            const auto* src = reinterpret_cast<uint8_t*>(&color);
            // Copy the color:
            *dest++ = *src++;  // R
            *dest++ = *src++;  // G
            *dest++ = *src++;  // B
        }
    }

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

#endif
}

void CImage::line(
    int x0, int y0, int x1, int y1, const mrpt::img::TColor color,
    unsigned int width, [[maybe_unused]] TPenStyle penStyle)
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    cv::line(
        m_impl->img, cv::Point(x0, y0), cv::Point(x1, y1),
        CV_RGB(color.R, color.G, color.B), static_cast<int>(width));
#endif
}

void CImage::drawCircle(
    int x, int y, int radius, const mrpt::img::TColor& color,
    unsigned int width)
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    cv::circle(
        m_impl->img, cv::Point(x, y), radius, CV_RGB(color.R, color.G, color.B),
        static_cast<int>(width));
#endif
}

void CImage::drawImage(int x, int y, const mrpt::img::CImage& img)
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();
    img.makeSureImageIsLoaded();

    cv::Rect roi(cv::Point(x, y), cv::Size(img.getWidth(), img.getHeight()));
    cv::Mat dest = m_impl->img(roi);
    img.m_impl->img.copyTo(dest);
#endif
}

void CImage::update_patch(
    const CImage& patch, const unsigned int col_, const unsigned int row_)
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    const auto& src = m_impl->img;
    auto& dest = patch.m_impl->img;

    src(cv::Rect(col_, row_, dest.cols, dest.rows)).copyTo(dest);
#endif
}

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
    const auto& src = m_impl->img;
    auto& dest = patch.m_impl->img;

    src(cv::Rect(col_, row_, col_num, row_num)).copyTo(dest);
#endif
}

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
}

void CImage::normalize()
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    cv::normalize(m_impl->img, m_impl->img, 255, 0, cv::NORM_MINMAX);
#endif
}

void CImage::getAsMatrix(
    CMatrixFloat& outMatrix, bool doResize, int x_min, int y_min, int x_max,
    int y_max, bool normalize_01) const
{
#if MRPT_HAS_OPENCV
    MRPT_START
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    const auto& img = m_impl->img;

    // Set sizes:
    if (x_max == -1) x_max = img.cols - 1;
    if (y_max == -1) y_max = img.rows - 1;

    ASSERT_(x_min >= 0 && x_min < img.cols && x_min < x_max);
    ASSERT_(y_min >= 0 && y_min < img.rows && y_min < y_max);

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

    if (doResize || outMatrix.rows() < ly || outMatrix.cols() < 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++)
        {
            const uint8_t* pixels = ptr<uint8_t>(x_min, y_min + y);
            for (int x = 0; x < lx; x++)
            {
                float aux = *pixels++ * 0.3f;
                aux += *pixels++ * 0.59f;
                aux += *pixels++ * 0.11f;
                if (normalize_01) aux *= (1.0f / 255);
                outMatrix.coeffRef(y, x) = aux;
            }
        }
    }
    else
    {
        for (int y = 0; y < ly; y++)
        {
            const uint8_t* pixels = ptr<uint8_t>(x_min, y_min + y);
            for (int x = 0; x < lx; x++)
            {
                float aux = (*pixels++);
                if (normalize_01) aux *= (1.0f / 255);
                outMatrix.coeffRef(y, x) = aux;
            }
        }
    }

    MRPT_END
#endif
}

void CImage::getAsRGBMatrices(
    mrpt::math::CMatrixFloat& R, mrpt::math::CMatrixFloat& G,
    mrpt::math::CMatrixFloat& B, 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
    const auto& img = m_impl->img;

    // Set sizes:
    if (x_max == -1) x_max = img.cols - 1;
    if (y_max == -1) y_max = img.rows - 1;

    ASSERT_(x_min >= 0 && x_min < img.cols && x_min < x_max);
    ASSERT_(y_min >= 0 && y_min < img.rows && y_min < y_max);

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

    if (doResize || R.rows() < ly || R.cols() < lx) R.setSize(ly, lx);
    if (doResize || G.rows() < ly || G.cols() < lx) G.setSize(ly, lx);
    if (doResize || B.rows() < ly || B.cols() < lx) B.setSize(ly, lx);

    if (isColor())
    {
        for (int y = 0; y < ly; y++)
        {
            const uint8_t* pixels = ptr<uint8_t>(x_min, y_min + y);
            for (int x = 0; x < lx; x++)
            {
                float aux = *pixels++ * (1.0f / 255);
                R.coeffRef(y, x) = aux;
                aux = *pixels++ * (1.0f / 255);
                G.coeffRef(y, x) = aux;
                aux = *pixels++ * (1.0f / 255);
                B.coeffRef(y, x) = aux;
            }
        }
    }
    else
    {
        for (int y = 0; y < ly; y++)
        {
            const uint8_t* pixels = ptr<uint8_t>(x_min, y_min + y);
            for (int x = 0; x < lx; x++)
            {
                R.coeffRef(y, x) = (*pixels) * (1.0f / 255);
                G.coeffRef(y, x) = (*pixels) * (1.0f / 255);
                B.coeffRef(y, x) = (*pixels++) * (1.0f / 255);
            }
        }
    }

    MRPT_END
#endif
}

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

    // 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 = static_cast<int>(getWidth());
    if (v_search_size == -1) v_search_size = static_cast<int>(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 < static_cast<int>(getWidth()));
    ASSERT_(v_search_end < static_cast<int>(getHeight()));

    // Find smallest valid size:
    size_t x, y;
    size_t actual_lx =
        std::max(static_cast<size_t>(u_search_size), in_img.getWidth());
    size_t actual_ly =
        std::max(static_cast<size_t>(v_search_size), in_img.getHeight());
    size_t lx = mrpt::round2up<size_t>(actual_lx);
    size_t ly = mrpt::round2up<size_t>(actual_ly);

    CMatrixF 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 -= biasThisImg;
    i1 -= biasInImg;

    // FFT:
    CMatrixF 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);

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

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

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

    // IFFT:
    CMatrixF 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
}

void CImage::getAsMatrixTiled(CMatrixFloat& outMatrix) const
{
#if MRPT_HAS_OPENCV
    MRPT_START

    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    const auto& img = m_impl->img;

    // The size of the matrix:
    const auto matrix_lx = outMatrix.cols();
    const auto matrix_ly = outMatrix.rows();

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

    MRPT_END
#endif
}

void CImage::clear()
{
    // Reset to defaults:
    *this = CImage();
}

void CImage::setExternalStorage(const std::string& fileName) noexcept
{
    clear();
    m_externalFile = fileName;
    m_imgIsExternalStorage = true;
}

void CImage::unload() const noexcept
{
#if MRPT_HAS_OPENCV
    if (m_imgIsExternalStorage) const_cast<cv::Mat&>(m_impl->img) = cv::Mat();
#endif
}

void CImage::makeSureImageIsLoaded() const
{
#if MRPT_HAS_OPENCV
    if (!m_impl->img.empty()) return;  // OK, continue
#endif

    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(
            "Trying to access uninitialized image in a non "
            "externally-stored "
            "image.");
    }
}

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

    if (m_externalFile[0] == '/' ||
        (m_externalFile[1] == ':' &&
         (m_externalFile[2] == '\\' || 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;
    }
}

void CImage::flipVertical()
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();
    cv::flip(m_impl->img, m_impl->img, 0 /* x-axis */);
#endif
}

void CImage::flipHorizontal()
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();
    cv::flip(m_impl->img, m_impl->img, 1 /* y-axis */);
#endif
}

void CImage::swapRB()
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    cv::cvtColor(m_impl->img, m_impl->img, cv::COLOR_RGB2BGR);
#endif
}

void CImage::rectifyImageInPlace(void* mapX, void* mapY)
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    auto& srcImg = m_impl->img;
    cv::Mat outImg(srcImg.rows, srcImg.cols, srcImg.type());

    auto mapXm = static_cast<cv::Mat*>(mapX);
    auto mapYm = static_cast<cv::Mat*>(mapX);

    cv::remap(srcImg, outImg, *mapXm, *mapYm, cv::INTER_CUBIC);

    clear();
    srcImg = outImg;
#endif
}

void CImage::undistort(
    CImage& out_img, const mrpt::img::TCamera& cameraParams) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    ASSERTMSG_(
        out_img.m_impl->img.data != m_impl->img.data,
        "In-place undistort() not supported");

    auto& srcImg = const_cast<cv::Mat&>(m_impl->img);
    // This will avoid re-alloc if size already matches.
    out_img.resize(srcImg.cols, srcImg.rows, getChannelCount());

    const auto& intrMat = cameraParams.intrinsicParams;
    const auto& dist = cameraParams.dist;

    cv::Mat distM(1, 5, CV_64F, const_cast<double*>(&dist[0]));
    cv::Mat inMat(3, 3, CV_64F);

    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++) inMat.at<double>(i, j) = intrMat(i, j);

    cv::undistort(srcImg, out_img.m_impl->img, inMat, distM);

#endif
}

void CImage::filterMedian(CImage& out_img, int W) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    auto srcImg = const_cast<cv::Mat&>(m_impl->img);
    if (this == &out_img)
        srcImg = srcImg.clone();
    else
        out_img.resize(srcImg.cols, srcImg.rows, getChannelCount());

    cv::medianBlur(srcImg, out_img.m_impl->img, W);
#endif
}

void CImage::filterGaussian(CImage& out_img, int W, int H, double sigma) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally
    auto srcImg = const_cast<cv::Mat&>(m_impl->img);
    if (this == &out_img)
        srcImg = srcImg.clone();
    else
        out_img.resize(srcImg.cols, srcImg.rows, getChannelCount());

    cv::GaussianBlur(srcImg, out_img.m_impl->img, cv::Size(W, H), sigma);
#endif
}

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

    auto srcImg = m_impl->img;
    // Detect in-place operation and make a deep copy if needed:
    if (out_img.m_impl->img.data == srcImg.data) srcImg = srcImg.clone();

    // Already done?
    if (out_img.getWidth() == width && out_img.getHeight() == height)
    {
        out_img.m_impl->img = srcImg;
        return;
    }
    out_img.resize(width, height, getChannelCount());

    // Resize:
    cv::resize(
        srcImg, out_img.m_impl->img, out_img.m_impl->img.size(), 0, 0,
        interpolationMethod2Cv(interp));
#endif
}

void CImage::rotateImage(
    CImage& out_img, double ang, unsigned int cx, unsigned int cy,
    double scale) const
{
#if MRPT_HAS_OPENCV
    makeSureImageIsLoaded();  // For delayed loaded images stored externally

    auto srcImg = m_impl->img;
    // Detect in-place operation and make a deep copy if needed:
    if (out_img.m_impl->img.data == srcImg.data) srcImg = srcImg.clone();

    out_img.resize(getWidth(), getHeight(), getChannelCount());

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

    // Apply rotation & scale:
    double m[2 * 3] = {scale * cos(ang), -scale * sin(ang), 1.0 * cx,
                       scale * sin(ang), scale * cos(ang),  1.0 * cy};
    cv::Mat M(2, 3, CV_64F, m);

    double dx = (srcImg.cols - 1) * 0.5;
    double dy = (srcImg.rows - 1) * 0.5;
    m[2] -= m[0] * dx + m[1] * dy;
    m[5] -= m[3] * dx + m[4] * dy;

    cv::warpAffine(
        srcImg, out_img.m_impl->img, M, out_img.m_impl->img.size(),
        cv::INTER_LINEAR + cv::WARP_INVERSE_MAP, cv::BORDER_REPLICATE);
#endif
}

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;

    auto& img = m_impl->img;

    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");

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

    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::img::TColor::blue());
        }
    }

    return true;
#else
    return false;
#endif
}

CImage CImage::colorImage() const
{
    CImage ret;
    colorImage(ret);
    return ret;
}

void CImage::colorImage(CImage& ret) const
{
#if MRPT_HAS_OPENCV
    if (this->isColor())
    {
        if (&ret != this) ret = *this;
        return;
    }

    auto srcImg = m_impl->img;
    // Detect in-place op. and make deep copy:
    if (srcImg.data == ret.m_impl->img.data) srcImg = srcImg.clone();

    ret.resize(getWidth(), getHeight(), CH_RGB);

    cv::cvtColor(srcImg, ret.m_impl->img, cv::COLOR_GRAY2BGR);
#endif
}

void CImage::joinImagesHorz(const CImage& img1, const CImage& img2)
{
#if MRPT_HAS_OPENCV
    ASSERT_(img1.getHeight() == img2.getHeight());

    auto im1 = img1.m_impl->img, im2 = img2.m_impl->img, img = m_impl->img;
    ASSERT_(im1.type() == im2.type());

    this->resize(im1.cols + im2.cols, im1.rows, getChannelCount());

    im1.copyTo(img(cv::Rect(0, 0, im1.cols, im1.rows)));
    im2.copyTo(img(cv::Rect(im1.cols, 0, im2.cols, im2.rows)));
#endif
}  // end

void CImage::equalizeHist(CImage& out_img) const
{
#if MRPT_HAS_OPENCV
    // Convert to a single luminance channel image
    auto srcImg = m_impl->img;
    if (this != &out_img)
        out_img.resize(srcImg.cols, srcImg.rows, getChannelCount());
    auto outImg = out_img.m_impl->img;

    if (srcImg.channels() == 1)
        cv::equalizeHist(srcImg, outImg);
    else
        THROW_EXCEPTION("Operation only supported for grayscale images");
#endif
}

// See: https://github.com/MRPT/mrpt/issues/885
// This seems a bug in GCC?
#if defined(__GNUC__)
#define MRPT_DISABLE_FULL_OPTIMIZATION __attribute__((optimize("O1")))
#else
#define MRPT_DISABLE_FULL_OPTIMIZATION
#endif

template <unsigned int HALF_WIN_SIZE>
void MRPT_DISABLE_FULL_OPTIMIZATION image_KLT_response_template(
    const uint8_t* in, const int widthStep, unsigned int x, unsigned int y,
    int32_t& _gxx, int32_t& _gyy, int32_t& _gxy)
{
    const auto min_x = x - HALF_WIN_SIZE;
    const auto 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, ++ptr)
        {
            const int32_t dx =
                static_cast<int32_t>(ptr[+1]) - static_cast<int32_t>(ptr[-1]);
            const int32_t dy = static_cast<int32_t>(ptr[+widthStep]) -
                               static_cast<int32_t>(ptr[-widthStep]);
            gxx += dx * dx;
            gxy += dx * dy;
            gyy += dy * dy;
        }
    }
    _gxx = gxx;
    _gyy = gyy;
    _gxy = gxy;
}

float MRPT_DISABLE_FULL_OPTIMIZATION CImage::KLT_response(
    const unsigned int x, const unsigned int y,
    const unsigned int half_window_size) const
{
#if MRPT_HAS_OPENCV

    const auto& im1 = m_impl->img;
    const auto img_w = static_cast<unsigned int>(im1.cols),
               img_h = static_cast<unsigned int>(im1.rows);
    const int widthStep = im1.step[0];

    // 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 auto* img_data = im1.ptr<uint8_t>(0);
    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* p = img_data + widthStep * yy + min_x;
                for (unsigned int xx = min_x; xx <= max_x; xx++)
                {
                    const int32_t dx = p[+1] - p[-1];
                    const int32_t dy = p[+widthStep] - p[-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
}

// 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::img::CImage& out_RGB,
    mrpt::img::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);
    out_alpha.resize(width, height, CH_GRAY);

    size_t idx = 0;
    for (int r = 0; r < height; r++)
    {
        const auto actual_row = origin_is_low_corner ? (height - 1 - r) : r;
        auto& img = out_RGB.m_impl->img;
        auto data = img.ptr<uint8_t>(actual_row);

        auto& img_alpha = out_alpha.m_impl->img;
        auto data_alpha = img_alpha.ptr<uint8_t>(actual_row);

        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
}

std::ostream& mrpt::img::operator<<(std::ostream& o, const TPixelCoordf& p)
{
    o << "(" << p.x << "," << p.y << ")";
    return o;
}
std::ostream& mrpt::img::operator<<(std::ostream& o, const TPixelCoord& p)
{
    o << "(" << p.x << "," << p.y << ")";
    return o;
}