comparer les histogrammes des images en niveaux de gris dans opencv

Voici le simple extrait de code qui fait la chose. Depuis que vous avez pas dit comment vous voulez comparer des histogrammes, je vous suggère de le faire visuellement.

#include <opencv2/opencv.hpp>
void show_histogram(std::string const& name, cv::Mat1b const& image)
{
//Set histogram bins count
int bins = 256;
int histSize[] = {bins};
//Set ranges for histogram bins
float lranges[] = {0, 256};
const float* ranges[] = {lranges};
//create matrix for histogram
cv::Mat hist;
int channels[] = {0};
//create matrix for histogram visualization
int const hist_height = 256;
cv::Mat3b hist_image = cv::Mat3b::zeros(hist_height, bins);
cv::calcHist(&image, 1, channels, cv::Mat(), hist, 1, histSize, ranges, true, false);
double max_val=0;
minMaxLoc(hist, 0, &max_val);
//visualize each bin
for(int b = 0; b < bins; b++) {
float const binVal = hist.at<float>(b);
int   const height = cvRound(binVal*hist_height/max_val);
cv::line
( hist_image
, cv::Point(b, hist_height-height), cv::Point(b, hist_height)
, cv::Scalar::all(255)
);
}
cv::imshow(name, hist_image);
}
int main (int argc, const char* argv[])
{
//here you can use cv::IMREAD_GRAYSCALE to load grayscale image, see image2
cv::Mat3b const image1 = cv::imread("C:\\workspace\\horse.png", cv::IMREAD_COLOR);
cv::Mat1b image1_gray;
cv::cvtColor(image1, image1_gray, cv::COLOR_BGR2GRAY);
cv::imshow("image1", image1_gray);
show_histogram("image1 hist", image1_gray);
cv::Mat1b const image2 = cv::imread("C:\\workspace\\bunny.jpg", cv::IMREAD_GRAYSCALE);
cv::imshow("image2", image2);
show_histogram("image2 hist", image2);
cv::waitKey();
return 0;
}

Résultat: