| Re: background colour in contour plots [message #9873] |
Thu, 28 August 1997 00:00 |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Ioannis Marangopoulos writes:
> I'm using pv-wave to create contour plots of an ultrasound
> field.When the plots appear on screen the background is black,
> however when the postcript file is created and printed is coming
> out with a white background.The white background is convenient
> in most cases, however in order to have good contrast for some of my colours
> -contours(eg yellow doesn't look good on white background!)
> I need to get the background black.This works only if I snapshot the plot off
> the screen.Any ideas on how to change the background into black in the postcript
> file??
This answer comes from one of the many tips on PostScript output
that you will find on my web page.
************************************************************ *******
The !P.BACKGROUND system variable is set to 255 when you make the
PostScript device active. But it doesn't matter what color you load into
color index 255, you still get a white background on your PostScript
plot! In other words, the color you load into index 255 can be used for
other things (as a drawing color, for example), but it doesn't affect the
background color of the plot.
There is only one way to get a background color different from white in a
PostScript file, and that is essentially to draw an image of a single
color in the PostScript window. I like to use POLYFILL for this purpose,
like this:
TVLCT, [255,0], [0,255], [0,0], !D.N_COLORS-2
greenColor = !D.N_COLORS-1
redColor = !D.N_COLORS-2
POLYFILL, [1,1,0,0,1], [1,0,0,1,1], /NORMAL, COLOR=greenColor
PLOT, data, COLOR=redColor, /NOERASE
Another way would be to use the TV command like this:
image = REPLICATE(greenColor, 2, 2)
TV, image, XSIZE=!D.X_SIZE, YSIZE=!D.Y_SIZE
PLOT, data, COLOR=redColor, /NOERASE
************************************************************ ********
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Customizable IDL Programming Courses
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com
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