Down by the Lake


I always find it more effective to learn new programming concepts by building projects using them, so I decided to do the same for Apple's new Swift language. I also wanted to see how well it would interact with my open source GPUImage framework. As a result, I made GPUImage fully Swift-compatible and I've built and committed to the GitHub repository a couple of Swift sample applications. I wanted to write down some of the things that I learned when building these.

Read on for more about my explorations of Swift using GPUImage.


I recently pushed a significant set of changes to the GPUImage repository, and wanted to explain them in a little more detail, especially since this changes one part of the manual photo filtering process. These changes should dramatically reduce the overall memory usage of the framework, help to prevent memory-related crashes, and fix a number of subtle bugs that have plagued the framework since I started it.

Read on for more about these changes.


With the launch of iOS 7, and its use of blurs throughout the interface, there's been a lot of interest in fast ways of blurring content. GPUImage has had a reasonably performant, but somewhat limited Gaussian blur implementation for a while, but I've not been happy with it. I've completely rewritten this Gaussian blur, and it now supports arbitrary blur radii while still being tuned for the iOS GPUs. At higher blur radii, I'm slower than Core Image, though, and I don't quite understand why.

Read on for more about the techniques I've used for GPU optimization of a Gaussian blur, as well as some interesting iOS benchmarks.

Molecules icon

It's been a little while since the last update, but version 2.1 of Molecules just went live on the App Store. 2.1 adds full support for the new Retina iPad, and has an enhanced rendering engine to support the detail on that newer device. I've also improved the contrast slightly on newer devices.

For iPad users, I've also added an atomic color key, which I know has been a highly requested feature. I've yet to rework the iPhone / iPod touch interface to support this, so this is not present on those devices.

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