Chroma Key Touchup

Chroma Key Touchup allows you to fix up your chroma key backgrounds with simple touch gestures. With improved chroma key algorithms that support green and blue screen backdrops, background removal has never been this easy or this fun.

Five easy steps, have your photo ready to share in minutes
1) Snap a photo
2) Automatic background removal
3) Touch up any mistakes with easy drawing tools
4) Select from one of the included backdrops or use your own
5) Share with family and friends

Get amazing blue screen and green screen (chroma key) effects on your phone or tablet.
Backgrounds include fantasy, sci-fi, sports, cartoons and more.

https://en.wikipedia.org/wiki/Chroma_key
"Chroma key compositing, or chroma keying, is a special effects / post-production technique for compositing (layering) two images or video streams together based on color hues (chroma range). The technique has been used heavily in many fields to remove a background from the subject of a photo or video"