Precise Bicubic

[everwicked]

How is it possible to use Precise Bicubic resize instead of Sharp or Soft in Gordian Knot?

And what setting is best if ofcourse you can adjust it? A=-0.75, A=-0.6 A=-1.0?

[Fox Mulder]

BicubicResize:

BicubicResize([b,c,]target-width,target-height,clip)
BicubicResize([b,c,]source-left,source-top,source-width,source-height,target-width,target-height,clip)

BicubicResize is similar to BilinearResize, except that instead of a linear filtering function it uses the Mitchell-Netravali two-part cubic. The parameters b and c can be used to adjust the properties of the cubic. With b = 0 and c = 0.75 the filter is exactly the same as VirtualDub's "precise bicubic," and the results are identical except for the VirtualDub scaling problem mentioned above. The default is b = 1/3 and c = 1/3, which were the values recommended by Mitchell and Netravali as yielding the most visually pleasing results in subjective tests of human beings. Larger values of b and c can produce interesting op-art effects--for example, try b = 0 and c = -5.

If you are magnifying your video, you will get much better-looking results with BicubicResize than with BilinearResize. However, if you are shrinking it, you are probably just as well off, or even better off, with BilinearResize. Although VirtualDub's bicubic filter does produce better-looking images than its bilinear filter, this is mainly because the bicubic filter sharpens the image, not because it samples it better. Sharp images are nice to look at--until you try to compress them, at which point they turn nasty on you very quickly. The BicubicResize default doesn't sharpen nearly as much as VirtualDub's bicubic, but it still sharpens more than the bilinear. If you plan to encode your video at a low bitrate, I wouldn't be at all surprised if BilinearResize yields better quality.

This is a quote from the Avisynth scripting language reference guide found in Avisynth's page at: www.math.berkeley.edu/~benrg/avisynth-reference.html You can find more info on the settings there.

If you want to change the resizing method you have to save, and then manually edit your .avs script.

Hope that helps :)

[everwicked]

Very nice my friend, a reference always helps ;)

Maybe i can find some more interesting things there.

By the way setting 1/3 + 1/3 is Soft Bicubic in Gknot and it gave better results for me even though most people recommend Sharp Bicubic. Maybe it's my eyes :eek:

If you click the Edit button before you save the .avs you can edit it on the fly :)

Thanks