Stack Motion is a fin new app that helps you cut somebody or something out of your photos and overlay it on top of another photo, or even a video. That’s pretty much the whole premise right there, but there are some clever features to help make it easy.
Step one: separate your subject from the background.
This is the hardest part of any composite, and his is where most of the work is done. The app helps out by trying to auto-detect the edges of your subject, and you can zoom and undo/redo your masking efforts until you get it just right.
Then steps 2–5 are straightforward. You can either just overlay one photo on another (boring), put a slideshow under the subject (better) or overlay the original photo on a video (awesome). You can even add music before sharing it to the usual places (I’m not sure if it makes animated GIFs, but it probably should).
I’m off to download the $2 app and use it to recreate every pop music video from the 1980s, right there on my iPhone.
Source: App Store.