anyone know how to make these green-magenta special effects? i circled them with red lines. thanks. i also want to know why are artists doing this? what does it mean? it means that there is motions or something?
Kinda easy one!
Merge your painting down to one layer and then duplicate your layer.
Now go into the duplicated layers options and turn one of the color channels off (like red for example).
Afterwards you just need to move your duplicated layer a few pixels to the left or to the right and done!
You'll see how the effect changes while moving the duplicated layer.
Sounds a bit complicated, but just try it out and you'll understand!
Nemome already explained, but maybe this tutorial also helps: http://fav.me/d4bywqk
I think besides looking cool it is meant to emulate a photographic effect, as this is a distortion that can happen when taking photos. Google chromatic aberration if you want to know more