I recently learned how to do this, and it's super easy! Useful for scenes that need an extra "OOMPH" of visual drama-- such a fight or a transformation, for example. Google will probably have better tutorials than I can make on it, but if you search "Photoshop RGB Split Effect" there are lots of Youtubers eager to teach you. This is the first time I've used it in the comic, but I'll likely be experimenting with it more in the future! ;)