#include <opencv2/core.hpp>

#include <opencv2/imgproc.hpp>

#include <opencv2/imgcodecs.hpp>

#include <iostream>

#include <vector>

using namespace std;

using namespace cv;

int main(int /*argc*/, const char** /* argv */ )

{

Mat framebuffer( 160 * 2, 160 * 5, CV_8UC3, cv::Scalar::all(255) );

Mat img( 160, 160, CV_8UC3, cv::Scalar::all(255) );

// Create test image.

{

const Point center( img.rows / 2 , img.cols /2 );

for( int radius = 5; radius < img.rows ; radius += 3 )

{

cv::circle( img, center, radius, Scalar(255,0,255) );

}

cv::rectangle( img, Point(0,0), Point(img.rows-1, img.cols-1), Scalar::all(0), 2 );

}

// Draw original image(s).

int top = 0; // Upper images

{

for( int left = 0 ; left < img.rows * 5 ; left += img.rows ){

Mat roi = framebuffer( Rect( left, top, img.rows, img.cols ) );

img.copyTo(roi);

cv::putText( roi, "original", Point(5,15), FONT_HERSHEY_SIMPLEX, 0.5, Scalar::all(0), 2, 4, false );

}

}

// Draw lossy images

top += img.cols; // Lower images

{

struct test_config{

string comment;

uint32_t sampling_factor;

} config [] = {

{ "411", IMWRITE_JPEG_SAMPLING_FACTOR_411 },

{ "420", IMWRITE_JPEG_SAMPLING_FACTOR_420 },

{ "422", IMWRITE_JPEG_SAMPLING_FACTOR_422 },

{ "440", IMWRITE_JPEG_SAMPLING_FACTOR_440 },

{ "444", IMWRITE_JPEG_SAMPLING_FACTOR_444 },

};

const int config_num = 5;

int left = 0;

for ( int i = 0 ; i < config_num; i++ )

{

// Compress images with sampling factor parameter.

vector<int> param;

param.push_back( IMWRITE_JPEG_SAMPLING_FACTOR );

param.push_back( config[i].sampling_factor );

vector<uint8_t> jpeg;

(void) imencode(".jpg", img, jpeg, param );

// Decompress it.

Mat jpegMat(jpeg);

Mat lossy_img = imdecode(jpegMat, -1);

// Copy into framebuffer and comment

Mat roi = framebuffer( Rect( left, top, lossy_img.rows, lossy_img.cols ) );

lossy_img.copyTo(roi);

cv::putText( roi, config[i].comment, Point(5,155), FONT_HERSHEY_SIMPLEX, 0.5, Scalar::all(0), 2, 4, false );

left += lossy_img.rows;

}

}

// Output framebuffer(as lossless).

imwrite( "imgcodecs_jpeg_samplingfactor_result.png", framebuffer );

return 0;

}