no subject (file transmission)

[Steve Franklin]

Message
Id: <92Sep24.103218adt.26901 at ug.cs.dal.ca>

Well, I approached this forum earlier on in my attempt to resolve my
greyscale problem. I did try the solution suggested to me, but it
didn't have much of an effect. I was still left with a maximum bandwidth
of about 8 greyscales which was most insufficient.
   Now however, it seems I have achieved somewhat of a temporary fix.
Using any standard image enhancing program (I used xv), I modified
the rgb proportions to be other than 1:1:1. Thus, although for intensive
purposes it appeared to be grayscale, it was actually made up of green
and blue combinations (while removing red). 
   The result of this was that I had a raster file I could bring into
grass with superb resolution. The only problem is the garbage colors
between 220-255. For some reason it is unable to reset those and I 
receive the error:
reset_color: can't set color 212
reset_color: can't set color 213
etc...
Now, I tried to use r.colors (rules) to map the rest of the upper colors
(200-255) to white, since they don't play much of a part in the map's
resolution. The only problem is that as soon as I add or change the
color scheme (mapset/colr/*.cell) at all, the entire image becomes
distorted and loses it's resolution.
   Now, although I realize that few are manipulating greyscale images
as such, I was hoping that you might have one or two solutions that
could deal with such a problem? How can I append the mapping for
the upper colors, and still maintain this cheat/fix I seem to have
stumbled on? 
   thanks in advance
Steve Franklin
p.s. If there are any more details you would like to know surrounding
my set up, do not hesitate to mail me at franklin at ug.cs.dal.ca.