Any digital image is actually red green and blue, those are the colors of the pixels on your monitor. When there's enough of them your brain is tricked into seeing other colors. To get even more meta, all colors are just made up by your brain.

So I don't understand your distinction between black and white, and grayscale. Whether it's a gray made of black and white pixels or a "pure gray" doesn't matter, it can look the same. Unless it's a style where the pixels are supposed to be visible, e.g. pointillism.