Masking in Photoshop is a useful technique for creating composite images, where multiple subjects, isolated from an original image, can be arrayed on a blank canvas, for example, to convey an overall sense of rhythm.
Computational photography technology is reaching into every aspect of modern photography, with smartphones leading the way. It's a great time to be a photographer.
Focus stacking is a computational process for manipulating depth-of-field, and is especially useful for landscape and macrophotography. The author gets down and dirty with the nuts and bolts of this powerful technique.