Color Correction is the process of any image looking different color from the Original. Color will be separated by Clipping Path or Alpha. When need to Color change in every places of an image, need to 100% quality clipping path for color Separation.
When the images is zoomed for show the large size path will be visible if color change is done by created alpha then separated with layer using alpha that situation problem is not raised. So in Color Correction, layer separate with Alpha give standard quality compare with Clipping.