I'm pleased to announce that version 1.3 of my book, Core Image for Swift, is now available through Apple's iBooks Store and, as a PDF, through Gumroad.
The main change is a new chapter discussing vImage - the image processing component of Accelerate. I focus mainly on the histogram and morphology functions: what they offer that "vanilla" Core Image lacks and how to integrate them in a Core Image workflow. Operations such as histogram stretching and equalisation are fantastically powerful tools and the new version of the book includes plenty of content explaining how they work and what they can do.
If you'd prefer to see and hear me ramble on about image processing, above is a video of me talking about Core Image at a recent NSLondon.
I'd suggest the iBooks version which includes video assets that the PDF version lacks.