Comparing with grayscale image, there`s a small change on our list of Painters, Blockers, Shifters, Mixers and Transformators. Let`s take a look...

First, let see some gradients just appending the channels from our favorite gradient source...

Also, will be very unfair if we don`t use the contrary and take our data from the image channels. To do that, we gonna use some external texture.

Going deeper, let`s take a look to some color math. Observe that the color brightness is changes my multiply and divide being one the opposite of the other. Also, observe the Power function (the same of multiply the value by itself) and observe how this operation adds saturation.

By now, I'm pretty sure that you understood that Colorful images are much more than several grayscale images on different channels (actually, looking with programmers eye, yes, a colored images are just that). So let`s see some Photoshop like effects here: