Afterimage (shader effect)

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For other uses, see Afterimage (disambiguation).

Afterimage is a computer graphics effect used by computer games. The effect takes the bright parts of a rendered image of the scene, and then fades in a motion blur style fashion as the scene progresses. The result is that bright areas leave a fading trail when the camera is moving. Afterimage can be used to enhance blooming. In some games, the process is named light trail.

The process looks something like the following:

CopyCurrentScreenTo(bloomBuffer);
BlurAndThreshold(bloomBuffer);
for_each(numberOfPasses, ApplyBloomToBuffer(bloomBuffer));
CombineBuffers(bloomBuffer, afterImageBuffer, screenBuffer);
Copy(bloomBuffer, afterImageBuffer); // store for next time