[PD-dev] [GEM] pix_convolve

hi

i had a look at pix_convolve over the past two days, and i just committed my changes:

- yuv support added - massive speed improvement by using integer processing (at least 2x but 5x in some cases) - removed the range divide (only added insult to the injury) - yuv function has option to discard chroma for accurate edge-detection - added an #ifdef so RGB works properly on OSX

i'm going to write a 3x3 specific function this weekend and see what sort of optimizations can be done with using greater number of registers, unrolled loops, etc. i'll give altivec a shot too. maybe at that point it will be useful to write abstractions based on pix_convolve. now, at least it's somewhat usable on machines available today.

cgc