• importare in AviSynth il plug-in di Virtualdub
• usare Xsharpen per VirtualDub e importarlo in AVS con la funzione già scritta da qualcun'altro
• usare un'altro sharpening nativo per AVS

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

This is a simple 3x3-kernel blurring filter. The largest allowable argument for Blur is about 1.58, which corresponds to an even 3x3-pixel blur. 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.