[comp.sys.sgi] Dithering

mberger@RELAY.NSWC.NAVY.MIL (07/18/90)

     Does any one have any dithering functions/programs?

     I am trying to convert a 256 color grayscale image into a 16
color grayscale image.  I have tried a straight conversion, as well
as the ordered dither, and error diffusion algorithms described in
'Fundamentals of Interactive Computer Graphics'.  All of these methods
give very contoured images.

                                             Thanks in advance
                                             Mike

markov@cs.ruu.nl (Mark Overmars) (05/22/91)

If I use double buffered drawing on a Personal Iris I have only 12 bitplanes.
Now the machine start using dithering when working in RGB mode. My first
question is:

 - Can you switch off dithering?

If not my second question is:

 - How should I choose my color such that there is no dithering?

I thought this where multiples of 16 but that does not seem to be correct (or
is it)?

Mark Overmars