Hi mate , I need RGB-->Grayscale_redness image that is to convert the more a pixel appears as red in the RGB image, the brighter it will be in the converted image.More specifically, it performs an RGB to Lab* color space conversion, then maps a range of a* values to grayscale values, such that white is assigned to the highest a* value resulting from the conversion, and black is assigned to a positive a* value determined by an algorithm parameter. How can I do ? Use Imgproc.cvtColor ( scr, dst , RGB2Lab ) or use Imgrpc.cvtColor( scr , dst , RGB2Gray ) and equalizeHist( scr, dst ) ? help me Please ? Thanks .