How to calculate peak signal-to-noise ratio (PSNR) for RGB color image in Matlab?

I made a project on image enhancement and I want to measure the PSNR for the enhanced RGB color image. I have also the reference RGB color image. I know there is a function in Matlab (psnr()). however I want to know if I can use this function to calculate the PSNR for the whole RGB color image i.e. use the following instruction in Matlab :

PSNR= psnr(A,Ref); % A is the enhanced RGB color image and REF is the reference RGB color image.

My question is : Is this instruction produces the correct PSNR value for the enhanced RGB color image or I have to calculate the PSNR for each channel separately ?

Answer 1

[Image Analyst]

The help does not specify that it must be a 2-D gray scale image so I assume it would work for an RGB image, which makes sense since it's just an element-by-element comparison so as long as the dimensions of both the test image and reference image match, it should work.

[ghada sandoub]

Thank you so much for your help