RGB to YIQ color space conversion for a image

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Like explained here, you need to write your own conversion function for that. It can be retrieved in the middle of the page!

However, if you can accept that the fact that your result is a bit less smooth, the HSV color space has similar results:

Mat original_image = imread("path_to_image");
Mat converted_image = original.clone();
cvtColor(original_image, converted_image, CV_BGR2HSV);