On Thursday 21 February 2002 5:55 pm, Mike Ressler wrote: > 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
Thanks, Mike. I'll take the xv code. A
