Bruce Bowyer-Smith has gone to the extraordinary effort to write a pack of GPU-accelerated effects for Paint.NET. It started out with a preview discussion in Plugin Developer’s Central that eventually led to a recent “public” release over in the normal Plugin publishing section.

The pack contains GPU accelerated versions of Gaussian Blur, Motion Blur, Radial Blur, Zoom Blur, as well as a new Channel Blur.

A GPU that supports DirectCompute is required along with Windows 7, or Windows Vista SP2 with the Platform Update (it needs DirectX 11, in other words). Most recent NVIDIA and ATI/AMD cards support this, although Intel’s do not. The latter is a big reason why I have not properly pursued this for Paint.NET yet – there is no high-performance software fallback for DirectCompute. (The “reference driver” does work, but is very slow because it’s intended to render “perfectly” without any regard to performance, and is mostly useful for GPU and driver engineers to make sure they are on the right track.)

It’s interesting to watch these effects execute, because they aren’t any faster on smaller images (and often slower). However, as the size of the image increases, the performance delta becomes very dramatic. The GPU versions just don’t seem to run any slower, while the CPU-based effects quickly lag far behind. These effects are probably hindered by Paint.NETs CPU-centric rendering model, so I wouldn’t be surprised if further performance jumps are possible.

The only downside I’m seeing is that, so far, it is limited to handling images that fit within the maximum texture size that your GPU supports. On a high end video card, that means 8,192 x 8,192 pixels (IIRC).

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