Speeding up Floyd-Steinberg dithering: an optimization exercise

Hi I shaved off 40% more just by replacing multiplication with bitwise operations and ported the code to a standard Python C Extension to avoid relying on JIT.

https://github.com/szabolcsdombi/optimized-floyd-steinberg-d...

X * 7 is equal to (X << 3) - X

X * 3 is equal to (X << 1) + X

X * 5 is equal to (X << 2) + X