I needed to transform my image (RGB stored in .jpg) to highlight the specific area of it. Using ImageJ I found out that extraction of the L-channel of image in LAB color space is exactly what I need for further inspection. When implemented in C++ / OpenCV, the result is totally different from the ImageJ one (see pics ImageJ L-channel and OpenCV L-channel):
#include "opencv2/opencv.hpp"
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
using namespace cv;
using namespace std;
int main(){
vector <Mat> lab_planes;
Mat src, lab;
src = imread("Pic.jpg", CV_LOAD_IMAGE_COLOR);
cvtColot(src, lab, CV_BGR2Lab);
split(lab, lab_planes);
imshow("L", lab_planes[0]);
imshow("a", lab_planes[1]);
imshow("b", lab_planes[2]);
waitKey(0);
return 0;
}
I tried to google that and found out that there may be a problem in difference of storing ranges of channels (0 - 255 instead of 'correct' 0 - 100) or RGB-presentation, but I don't figure out how to receive same result as with ImageJ.
Thanks!
May be:
cv::normalize(L,L,0,255,cv::NORM_MINMAX);
Or (may be more correct) just multiply by 2.55 (first convert to CV_32F then multiply, and convert back).