Lee Elliott <[EMAIL PROTECTED]> writes: > Hello, > > I don't think that using 32bpp increases the number of colours that can > be used - 32bpp is generally used as 24bpp (8bpp each for RGB) + 8bpp > alpha channel. 16bpp is split R=5bpp, G=6bpp & B=5bpp. I've seen 36bpp > scanners and they do work with more colours - 12bpp each for RGB.
I've never seen the alpha channel actually being used, but the main advantage that 32bpp has over 24bpp is that it is/should be faster, since pixel addresses line up with word boundaries in 32bpp (each pixel is 4 bytes rather than 3 bytes). And, of course, the disadvantage is that it takes more memory. It wouldn't make much sense to have more than 16M colours on a screen, since 16M is about the number of colours that a person can see on a screen. Interestingly, people can see more colours on printed matter than on a screen, which may be one reason scanners use higher bit depths. Hubert
