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Jonas B

Multi-pass blur settings

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Has anyone got a good implementation of Kawase's multi-pass blur algorithm, as described in http://www.daionet.gr.jp/~masa/archives/GDC2004/GDC2004_PIoHDRR_SHORT_EN.ppt pages 34-37? With the filter kernel and the blend factors I use for each pass, the filter is too "spiky". How should these be set in order to approximate a Gaussian distribution? For an arbitrary blur size? I've experimented a bit and improved the results, but I'd like a mathematically derived solution instead of one based on guesswork...

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Unfortunately, no; that article describes a standard 1-pass blur. Kawase's blur uses N passes:
(pseudo)
for (i=0;i<N;i++)
surface = originalTexture.mipmap(i)
blur(surface, kernel)
resize(surface, pow(2,i))
blend(surface, finalSurface, blendFactor)

The idea is to simulate blurs with very large kernels.

I'm hoping someone has a way to calculate kernels and blendFactors to achieve better filter shapes than the one I've currently got.

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