Histogram matching of two images with c++ and OpenCV 2.4.x - c++

Question

Since I found nothing about Histogram Matching in C++ and OpenCV 2.4 I ask here again a question.
All solutions I found for newer versions.
My code:
void histogramMatching(Mat & reference, Mat & input, Mat & result) {
const float HISMATCH = 0.001;
double min, max;
vector<Mat> reference_channels;
split(reference, reference_channels);
vector<Mat> input_channels;
split(input, input_channels);
int histSize = 256;
float range[] = { 0,256 };
const float* histrange = { range };
bool uniform = true;
for (int i = 0; i < 3; i++) {
Mat reference_histogram, input_histogram;
Mat reference_histogram_accum, input_histogram_accum;
calcHist(&input_channels[i], 1, 0, Mat(), input_histogram, 1, &histSize, &histrange, &uniform);
try {
calcHist(&reference_channels[i], 1, 0, Mat(), reference_histogram, 1, &histSize, &histrange, &uniform);
}
catch (int n) {
cout << "The first element is " << n << endl;
}
minMaxLoc(reference_histogram, &min, &max);
normalize(reference_histogram, reference_histogram, min / max, NORM_MINMAX);
minMaxLoc(input_histogram, &min, &max);
normalize(input_histogram, input_histogram, min / max, NORM_MINMAX);
reference_histogram.copyTo(reference_histogram_accum);
input_histogram.copyTo(input_histogram_accum);
float* src_cdf_data = input_histogram_accum.ptr<float>();
float* dst_cdf_data = reference_histogram_accum.ptr<float>();
for (int j = 1; j < 256; j++) {
src_cdf_data[j] += src_cdf_data[j - 1];
dst_cdf_data[j] += dst_cdf_data[j - 1];
}
minMaxLoc(reference_histogram_accum, &min, &max);
normalize(reference_histogram_accum, reference_histogram_accum, min / max, 1.0, NORM_MINMAX);
minMaxLoc(input_histogram_accum, &min, &max);
normalize(input_histogram_accum, input_histogram_accum, min / max, 1.0, NORM_MINMAX);
//BEGIN Matching
Mat lut(1, 256, CV_8UC1);
uchar* M = lut.ptr<uchar>();
uchar last = 0;
for (int j = 0; j < input_histogram_accum.rows; j++) {
float F1 = dst_cdf_data[j];
int i = 0;
for (uchar k = last; k < reference_histogram_accum.rows; k++) {
i++;
float F2 = src_cdf_data[k];
if (abs(F2 - F1) < HISMATCH || F2 > F1) {
M[j] = k;
last = k;
break;
}
}
}
LUT(input_channels[i], lut, input_channels[i]);
}
merge(input_channels, result);
}
public:int execute() {
Mat input = imread("input.jpg", IMREAD_COLOR);
if (input.empty()) {
cout << "Image is empty" << endl;
return -1;
}
Mat reference = imread("fuchs.jpg", IMREAD_COLOR);
if (reference.empty()) {
cout << "Reference Image is empty" << endl;
return -1;
}
Mat result = input.clone();
namedWindow("Reference", WINDOW_AUTOSIZE);
namedWindow("Input", WINDOW_AUTOSIZE);
namedWindow("Result", WINDOW_AUTOSIZE);
imshow("Reference", reference);
imshow("Input", input);
histogramMatching(reference, input, result);
imshow("Result", result);
waitKey(0);
return 0;
}
All works, but the loop which begins with "for (int j = 0; j < input_histogram_accum.rows; j++) {", get no response and i waited for more than 6 hours and i think it doesn't work. My input image is 500kb and my fuchs.jpg is 180 kb.
Has anybody a solution for histogram matching with C++ and OpenCV 2.4.x?