Chapter 3. Blending Images

Let's complete our work on the LightWork app, which we started in Chapter 2, Capturing, Storing, and Sharing Photos. LightWork can already control the iOS device's cameras, capture an image, convert its format, save it, and share it via social media. However, the app is missing the ability to load and reprocess old images. We are going to change this by enabling the user to achieve the following results:

• Select an image from the user's Photos library.
• Select an algorithm that defines how to blend two images. We will support some simple arithmetic algorithms as well as an edge-finding algorithm that reduces one of the images to a line drawing.
• Using the selected blending algorithm, blend the selected image with the background. The background may be the LightWork app's static background image or a frame of live video from the camera.

Compared to the groundwork that we have already done, these additional features are simple, so this chapter...