How does psnr calculate the PSNR of PNG color images?

In my case, both input images are in PNG format, which (I expect to) consist of RGB values. The output is one PSNR value for each image.

Does it make sense to use psnr for PNG, or should I first make a conversion to YUV, and use psnr separately for the components?

Answer 1

[KSSV]

You can check how psnr is calculated from this file exchange: https://in.mathworks.com/matlabcentral/fileexchange/135-psnr.

You can use RGB image to calculate psnr.

[Seppo Valli]

Thank you for the quick answer.

I would prefer getting separate PSNR values for luminance and chrominance components (as being coded separately by my software, and affecting to the perceived quality differently). Even getting only the value for luminance is better compared to averaging over components.

Is there any other way for this than to make a conversion (e.g.) to YUV, and use psnr separately for the components?

I am doupting that when using psnr for PNG images, the PSNR is calculated and averaged over RGB values. Is it so?