title: How to apply edge detection filters on colored images on Sobel?
body: <p>I know how to do an image filter like the sobel-filter on 1 byte per pixel. However if you want to do it on RGB image with 24 bit per pixel, I don't know how to do it.</p>
  
  <p>What is the best way to do that without having to convert the RGB image to a 8 bit one (greyscale)? </p>