preview and birdseye

[Casper Boemann]

On Wednesday 04 January 2006 20:31, Cyrille Berger wrote:
> > 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.
But this is true for your suggestion as well

> 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.
Well that is same thing, so naturally the speed will be the same ;)

Only difference is that my suggestion does things like raindrops correctly 
while yours would not - But that comes at a price of slower calculation
-- 
best regards / venlig hilsen
Casper Boemann