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Blur Source Plugin

The Blur Source plugin

The Blur Source plugin will apply a variable amount of blur to a video source, horizontally, vertically, or both. The blur plugin works by taking the average of 7 neighboring "sample" pixels, first horizontally, then vertically. As you increase the amount of blur you want, the plugin increases how far apart the 7 samples are. This approach works well for small amounts of blurring, but if you want to create really extreme blurs, you need to take samples that are really far apart, however, since there are only 7 samples taken, you get something like this:

The image looks really weird and blocky because you're not sampling "enough" of the image to get real blurring. The plugin also includes a "passes" knob, which controls how many blurring passes are applied to the image. Using a smaller blur amount with more passes will result in much smoother looking blur. The images below were done with a high blur value, and four passes:

Improving Performance

The blur plugin uses render-to-texture, and makes two passes over the image for each actual pass you request (one horizontal and one vertical). Each pass samples up to 28 source pixels for every destination pixel written, so it can chew up a lot of memory bandwidth.

If you have an older video card, to increase performance you may wish to use fewer passes, or lower blur strength values. You can also use smaller source material - the blurring happens at either the resolution of the display, or the resolution of the source, whichever is smaller. Blurring a smaller source and stretching it to fill the screen will use a lot less fill rate.