我应该将像素的rgb值视为一个值吗？

Question

I was reading this paper for a project work using imagmagick and C++.

We train on 1.6 million 32*32 color images that have been preprocessed by subtracting from each pixel its mean value over all images and then dividing by the standard deviation of all pixels over all images.

I've trouble distinguishing between "from each pixel its mean value over all images" and "standard deviation of all pixels over all images".

Since, I'm dealing with color images, can I just take rgb values of each pixel as one value or should I calculate the mean and SD for every color differently?

For example if I have r=255, g=255, b=255, can I take pixel value as (in binary), (r<<16)+(g<<8)+b ?

Answer 1

Color channel values should be used independently. If you would use 32 bit representation of the pixels, you would get big value differences between very near colors which differ in red or green channel.