The multiplied overlay plus the filters create a wide variety of effects.
This tool creates a “depth map” to add parallax motion to static images.
I’d really like an image editor that has Automator actions. This one does, but I can’t afford it right now. It’s going on the list!
This editor is nice because it does all the standard things to images, but also lets you start from scratch and use layers.
I needed a technique like this on a project last year… eventually managed to hack something together, but this is definitely going in the reference files.