- /*
- * Modify colour entries with RGB = (255,0,255) to (255,0,254) if
- * mask colour is present (so that existing pixels with (255,0,255)
- * magenta colour are not incorrectly made transparent):
- */
+ // deal with the mask: we must replace pseudo-colour "None" with the mask
+ // colour (which can be any colour not otherwise used in the image)