On Tue, 11 Mar 2003 20:05:39 +0100, "Steinar H. Gunderson" <[EMAIL PROTECTED]> wrote:
> On Tue, Mar 11, 2003 at 10:15:51AM -0800, Daniel Rogers wrote:
> > Alpha is a measure of the amount of coverage of the pixel. (e.g. an
> > alpha of .5 means half the pixel is covered). In particular, 0 alpha
> > means that the pixel is not covered at all. This means that the pixel
> > contributes NO color information. I think this should hold for blur as
> > well. And from that point of view, no pixel with alpha zero should ever
> > contribute color information.
> How do you propose this being implemented, ie. what value would you plug into
> the IIR filter GIMP's blur is based on, for a pixel with alpha != 255?
You would not plug any color there, of course. Or more exactly, the
color would not matter because it would be multiplied by 0 anyway.
Please take a look at the formulas in these two bug reports:
The IIR Blur filter was also affected by that bug but it has been fixed
thanks to David Necas (Yeti):
Gimp-developer mailing list