In the above video, Photoshop Principal Product Manager Bryan O’Neil Hughes explains how to use Photoshop and Photoshop Mix together in order to do mobile masking, compositing, and make selections. You can find Photoshop Mix here on the iTunes App Store.
Masking, Compositing and Selections in Photoshop Mix for iPad
[youtube https://www.youtube.com/watch?v=_h-K2b6ewzo&w=700]