could a rgb image do dct and idct??

as title

I saw many example do dct and idct with graylevel image

but I have never seen using on a rgb or colorful image

could do it ??

Answer 1

[Jan]

And RGB image consists of 3 channels, which contain the intensity of the red green and blue signal. So you can treat it as 3 gray level images.

Using other color schemes is usually better for image compression, e.g. YUV.