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Re: Color question

David Fanning wrote:
> 
> R. Kyle Justice (rkj@dukebar.crml.uab.edu) writes:
> 
> > 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.
<SNIP>
> > 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


The immediate solution is to use *only* those colors as appear in
countours in the color bar. 

And no for loops are needed.  You could write:

bar=LINDGEN(200,1000)/(200*100)

or dispense with the chicanery altogether and simply use:

bar=1b#bindgen(10)
TV, bar, 0,0,XSIZE=.5,YSIZE=4,/inches


Using the /inches (or /centimeters) keyword to TV for postscript output
is highly advised.

I get the same pure yellow either way:  #ffff00

JD