[Gimp-developer] Selective gaussian blur port to gegl

[Karthikeyan S <karthikdevel gmail com>]

Hi all,

I am trying to port the selective gaussian blur filter to gegl. I do not understand the following lines in the original gimp code and what purpose they serve.

---

Line 668
if (has_alpha)
 d *= src_b[nb - b]; // ?
---

Line 676
if (has_alpha)
{
  rowsum >>= 8; // why?
  rowfact >>= 8;
}

---

Also, as of now, my implementation correctly maintains edges in checker board images while blurring other areas. I am trying to debug another issue wherein I see that the noise pixels (in complete dark background in the checkerboard image)  seem to get smeared out to neighbourhood areas and we get large patches of white arround the blurred pixel (This does not happen in gimp implementation). I am trying to see if the above lines have some clue to that.

Thanks,
Karthik