Re: RGB->HSI->RGB

"Pete" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> At present I'm using fp arithmetic to convert 3 byte rgb to 3 byte hsi.
> Unfortunately the reverse of this procedure does not give exactly the same
> rgb

That's impossible to avoid. Since there are different HSI combinations
that have the same RGB representation (for example S and I are zero,
with any hue, *becomes* black), you cannot make a one-to-one map
between all 24 bit RGB and HSI colors.

There's also some precision loss which you could avoid by using higher
precision HSI, although the inconvenience of that usually doesn't
weigh up against the small quality difference.

I assume "fp" means floating point? That's not really necessary for
RGB <-> HSI conversion, and it certainly won't help avoiding the
irreversability problem.