On Thu, 21 Feb 2002, Asger K. Alstrup Nielsen wrote:
> On Thu, 21 Feb 2002, Angus Leeming wrote:
> > and the problem is now defining an appropriate mapping from the colour
> > colourmap to a grayscale or monochrome one.
>
> I'm not sure what the problem is, but if you want to convert from
> color to grayscale, just do this:
>
> int gray = (red + blue + green) / 3;
Actually, the better way to do this is (xv Postscript code)
gray = 0.32 * red + 0.5 * green + 0.18 * blue
or perhaps (NTSC)
gray = 0.30 * red + 0.59 * green + 0.11 * blue
Either gives a better match to a human's RGB to luminance conversion.
Definitely not (R+G+B)/3!
Mike
--
Mike Ressler
[EMAIL PROTECTED]
OK, I'm lame: I don't have my own website ...
