Georgios Kapetanakis wrote: > > > > The routine I'm using is not very fast, but it's the best I can do (it > takes > > > approx. 35ms to execute). I think the fastest routine would be a precomputed lookup table. Use the BGR value as an index into a list of RGB values. Write another program to calculate the lookup table, possibly save it as a file so you can reload it instead of recalculating it. Drawback is that it uses a lot of memory: it would be about 67MB long if you use 32bit values (for efficiency and speed). Bit shifting takes a long time, possibly longer than byte-swapping, although byte swapping inside a register using assembler instructions might be as fast as table lookup. An optimising c compiler might translate bitshifts of 4 or 8 into swaps or it might not. Martin
