Blur

Blur(clip clip, float amount, bool MMX)
Blur(clip, float amountH, float amountV, bool MMX)
Sharpen(clip clip, float amount, bool MMX)
Sharpen(clip, float amountH, float amountV, bool MMX)

This is a simple 3x3-kernel blurring filter using the kernel [(1−2^−amount)/2, 2^−amount, (1−2^−amount)/2]. The largest allowable argument for Blur is log2(3) (which is about 1.58), which corresponds to a (1/3, 1/3, 1/3) kernel. A value of 1.0 gets you a (1/4, 1/2, 1/4) kernel. If you want a large-radius Gaussian blur, I recommend chaining several copies of Blur(1.0) together. (Anybody remember Pascal's triangle?)

Negative arguments to Blur actually sharpen the image, and in fact Sharpen(n) is just an alias for Blur(-n). The smallest allowable argument to Blur is -1.0 and the largest to Sharpen is 1.0.

You can use 2 arguments to set independent Vertical and Horizontal amounts. Like this, you can use Blur(0,1) to filter only Vertically, for example to blend interlaced lines together. By default amountV=amountH.

Changes

v2.58	MMX routines fixed (have full 8 bit precision now); mmx=true by default
v2.57	added MMX option