On Tue, 17 Aug 1999, Michael G. Schabert wrote:

> Although technically, there is no such beast as 16-bit color on the Mac,
> the same as there's no such thing as 32-bit color. Video color tables
> generally go:
> B&W (1-bit)
> 4-color (2bit)
> 16-color (4bit)
> 256-color (8bit)
> 32768-color (CALLED 16-bit)
> 16.7mill-color (CALLED either 24-bit or 32-bit, depending on the manufacturer)
> 
> The reason that they add in the extra bits is because there really is that
> much info travelling down the line...the extra bits are just used for
> "extra" control info instead of the color data itself.

There's a difference between 24-bit and 32-bit color. I've seen some video
boards where they really only populated three of the four bytes. :-) So
when they say 24-bit color, they don't guarantee that extra byte lane is
there. If they say 32-bit, that implies it's there. While it won't make a
visual difference, a number of graphics algorythms make use of the "alpha"
channel, which lives in the extra byte per pixel.

Take care,

Bill