Back in 2010, I gave a talk about the use of OpenGL shaders to accelerate image and video processing on mobile devices. The response from that talk was strong enough that two years later I started work on the open source framework GPUImage with the goal of making this kind of processing more accessible to developers. In an attempt to broaden the reach of this framework, today I'm introducing the completely-rewritten-in-Swift GPUImage 2 with support for Mac, iOS, and now Linux. This isn't just a port, it's a complete rewrite of the framework.

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.

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.

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.

I'd like to introduce a new open source framework that I've written, called GPUImage. The GPUImage framework is a BSD-licensed iOS library (for which the source code can be found on Github) that lets you apply GPU-accelerated filters and other effects to images, live camera video, and movies. In comparison to Core Image (part of iOS 5.0), GPUImage allows you to write your own custom filters, supports deployment to iOS 4.0, and has a slightly simpler interface. However, it currently lacks some of the more advanced features of Core Image, such as facial detection.