preview and birdseye

[Cyrille Berger]

> Well in that case one would have to figure out what neighbours are
> significanly affected by applying the effect to one pixel and how this
> would be propagated even further by applying the effect to the neighbours.
>
> By doing so it should be possible to find a _fraction_ of the
> source-image-makropixel (which represents the area that is covered by the
> respective pixel on the preview image) which will -- after applying the
> effect -- show almost the same results to the pixel as with filtering the
> full image. Depending on the size of the image this could give a huge boost
> to the filter preview indeed. While this also might not work for all
> filters this will probably work for most of them.
it won't work at all for auto contrast, wavelet noise reduction... and all 
filters that need the whole image to compute a parameter to then apply a 
modifiction to each pixel.

And I still fail to see how this can be faster, maybe more accurate for the 
"oil painter", I still don't see how it can be faster than reducing the 
image, and then applying the filter.

-- 
--- Cyrille Berger ---