Re: Color question

[rkj(at)dukebar.crml.uab.edu (R. Kyle Justice)]

Ok, here is some sample code that will hopefully demonstrate
problem of grainy colors using TV on a postscript device.  You
will need a color postscript printer to verify this.

SET_PLOT, 'PS'
DEVICE, Bits_Per_Pixel=8, /Color 
TEK_COLOR     ; or create your own discrete colormap
bar=BYTARR(200,1000)
FOR i=0,999 DO bar(*,i)=i*9/1000
TV, bar, /Device
PLOT, INDGEN(10), Color=7, Charthick=3, Thick=5, /Noerase
DEVICE, /Close

Print it out and you should see that the plot is a "pure"
yellow but the bar yellow is "grainy."

I guess there is a difference between a plot and an image 
on a postscript device.  Plots seem to use filled polygons 
(which give pure colors) while images appear to use pixels
or dots.

Kyle