> I actually benchmarked these two versions a while ago, and it turns out > that on a reasonably new PC (K6/PII or up), fixed point arithmetic is > quite a bit faster than tables - It turns out that a fixed point > multiply is a lot quicker than a memory access (especially when taking > the heavy cache usage of image processing into account). On older PCs > (Pentium/K5/etc) the table version is quicker. I almost asked about that with the original mail. I was also wondering about the timing implications of conversions from packed formats from the likes of 24bit RGB and the reverse when done with table lookup versus math and bit diddling. I rather like the idea of the table lookup, it sure has been a staple for a lot of speedups, but it seems that perhaps in the days of Gigahertz processors and 2CL SDRAM it might be a a tossup on what is faster for an application such as this. I suppose one of these days I will look at these timing issues. Thanks for all of the useful replies, too. Colin
