Blur

Revision as of 17:27, 21 September 2014

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. The largest allowable argument for Blur 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.

A Known issue, with the MMX routines is the lack of full 8 bit precision in the calculations. This can lead to banding in the resultant image. Set the MMX=False option to use the slower but more accurate C++ routines if this is a concern.

Changes