On Wed, 2007-04-25 at 09:08 +1000, Campbell Barton wrote:
> just did a simple test
> * 16x16 rgb image
> * select half (vertically in my case) and fill in
> * run the Gaussian blur, 1 blur pixel
> * Hold  Ctrl+F to rerun the filter many times
> - Image will eventually turn black
> - Happens for RLE and IIR

As explained already, that's slightly off-topic as we were discussing
the Blur tool, not the Gaussian Blur plug-in. But since you are bringing
it up, let's have a look at the plug-in as well...

What you describe sounds like a very artifical test. As I outlined
already, small rounding errors are hard to avoid. So it is not too
unlikely that, even for a rather stable algorithm, you can create a test
that, when repeated often enough, will give an error. Your test image is
very small, so the contribution from the border is large. But of course,
an ideal blur algorithm should deal correctly with that.

If we look at a larger test image filled with stripes of white and black
color, the plug-in seems to do its job rather well. So I don't think
there's urgent need to review the plug-in. But of course we will
appreciate any patches that improve the result without hurting the



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