Convert HSV To Grayscale In OpenCV


Answer :

The conversion from HSV to gray is not necessary: you already have it. You can just select the V channel as your grayscale image by splitting the HSV image in 3 and taking the 3rd channel:


Mat im = imread("C:/local/opencv248/sources/samples/c/lena.jpg", CV_LOAD_IMAGE_COLOR);
    
Mat imHSV;
cvtColor(im, imHSV, CV_BGR2HSV);
imshow("HSV", imHSV);
    
//cvtColor(imHSV, imHSV, CV_BGR2GRAY);
Mat hsv_channels[3];
cv::split( imHSV, hsv_channels );
imshow("HSV to gray", hsv_channels[2]);
    
imshow("BGR", im);
cvtColor(im, im, CV_BGR2GRAY);
imshow("BGR to gray", im);
    
waitKey();


hsv1 = cv2.cvtColor(frame1, cv2.COLOR_BGR2HSV)

h, s, v1 = cv2.split(hsv1)

cv2.imshow("gray-image",v1)


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