Example: img_basic_example

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2023, 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 <mrpt/gui/CDisplayWindow.h>
#include <mrpt/math/CMatrixF.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/CTimeLogger.h>

#include <iostream>

using namespace mrpt;
using namespace mrpt::gui;
using namespace mrpt::img;
using namespace mrpt::math;
using namespace mrpt::system;
using namespace std;

#include <mrpt/examples_config.h>
string myDataDir(MRPT_EXAMPLES_BASE_DIRECTORY + string("img_basic_example/"));

// ------------------------------------------------------
//              TestImageCap
// ------------------------------------------------------
void TestImageConversion()
{
    // BMP -> JPEG conversion tester:
    // --------------------------------
    CImage img;
    CTicTac tictac;
    CTimeLogger timlog;

    tictac.Tic();
    if (!img.loadFromFile(myDataDir + string("frame_color.jpg")))
    {
        cerr << "Cannot load " << myDataDir + string("frame_color.jpg") << endl;
        return;
    }
    printf("Image loaded in %.03fms\n", 1000 * tictac.Tac());

    if (false)  // A very simple test:
    {
        CDisplayWindow win1("JPEG file, color");
        win1.setPos(10, 10);

        win1.showImage(img);

        cout << "Push a key in the console or in the window to continue...";
        win1.waitForKey();
        cout << "Done" << endl;

        timlog.enter("grayscale1");
        img = img.grayscale();
        timlog.leave("grayscale1");

        CDisplayWindow win2("JPEG file, gray");
        win2.showImage(img);
        win1.setPos(300, 10);

        cout << "Push a key in the console or in the window to continue...";
        win2.waitForKey();
        cout << "Done" << endl;

        mrpt::system::pause();
        return;
    }

    CDisplayWindow win1("win1"), win2("win2"), win3("win3"), win4("win4");

    CImage imgSmall(img);
    CImage imgGray;

    for (int i = 0; i < 50; i++)
    {
        timlog.enter("grayscale2");
        imgSmall.grayscale(imgGray);
        timlog.leave("grayscale2");
    }

    CImage imgSmall2 = imgGray.scaleHalf(IMG_INTERP_LINEAR);
    CImage imgSmallRGB = img.scaleHalf(IMG_INTERP_LINEAR);

    // Test some draw capabilities:
    // ---------------------------------
    imgSmall.rectangle(85, 35, 170, 170, TColor(255, 0, 0), 10);

    imgSmall.line(550, 75, 650, 25, TColor(0, 0, 255));
    imgSmall.line(-10, -20, 20, 30, TColor(0, 0, 255));

    CMatrixDouble22 COV;
    COV(0, 0) = 100;
    COV(1, 1) = 50;
    COV(0, 1) = COV(1, 0) = -30;
    imgSmall.ellipseGaussian(COV, 600.0, 50.0, 2, TColor(255, 255, 0), 4);
    imgGray.ellipseGaussian(COV, 100.0, 100.0, 2, TColor(0, 0, 255), 4);

    imgGray.drawImage(50, 40, imgSmall2);

    // Show the windows now:
    // ------------------------------------------------------
    win1.showImage(imgSmall);
    win1.setPos(0, 0);
    win2.showImage(imgSmall2);
    win2.setPos(810, 0);
    win3.showImage(imgGray);
    win3.setPos(810, 300);
    win4.showImage(imgSmallRGB);
    win4.setPos(300, 400);

    cout << "Press any key on 'win4' to exit" << endl;
    win4.waitForKey();

    tictac.Tic();
    imgGray.saveToFile("frame_out.jpg");
    printf("jpeg file saved in %.03fms\n", 1000.0 * tictac.Tac());

    imgSmall2.saveToFile("frame_out_small.png");

    return;
}

// ------------------------------------------------------
//                      MAIN
// ------------------------------------------------------
int main()
{
    try
    {
        TestImageConversion();
        return 0;
    }
    catch (const std::exception& e)
    {
        std::cerr << "MRPT error: " << mrpt::exception_to_str(e) << std::endl;
        return -1;
    }
}