Many of the higher end photo editors on the iPhone and iPad let you add layers of photos over each other. Generally though, those apps require a bit of effort when moving layers around and are more positioned at creating very nice artist results. A ‘new to me’ app trying to make layers more usable for quick edits is Layover.
While Layover is easy to use, the universal app isn’t lacking any features. Think of Layover more on the Instagram side of editing than the Photoshop side. You can layer up to 5 photos into a single finished image. Included is 15 filters (Multiply, Screen, Layover, Soft Light, Hard Light, Color Dodge, Color Burn, Addition, Difference, Darken, Lighten, Hue, Saturation, Color and Luminosity) to apply to your images simply by dragging the photos to the filter.
These features would make Layover a great app to bring together many photos into a memorable finished image. But, there is another feature included to help bring out parts of photos and drop out other areas. Per the developer:
The Mask feature lets you erase specific parts of pictures to isolate elements, remove the background, and let different layers show through. Use the Mask slider to control how dramatic or subtle you want the erase marks to appear, and then swipe your finger across the areas you would like to erase.
When done, export to your friends on social sites or save to your iPhone’s photo library.