Why the images are converted from RGB scale to GRAY scale in MATLAB? Can I use a RGB scale image directly in MATLAB for de-noising?

Please suggest me some answer.

Answer 1

[Image Analyst]

Sometimes you don't need the color information or just need a certain color channel so you extract that. For example if I wanted to find bright green ball on a white background I would be best off just extracting the red or blue channel - they will be a monochrome image that I could then threshold to find dark regions corresponding to where the green ball is.

RGB images can be denoised in a variety of methods. It depends on what you mean by directly. Often they are denoised by extracting color channels, sometimes after conversion to another color space, like HSV.