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Re: How to do RGB to CMYK conversion for PS output? [message #49314 is a reply to message #49313]

Thu, 13 July 2006 12:23

Karl Schultz
Messages: 341
Registered: October 1999

Senior Member

On Thu, 13 Jul 2006 14:31:22 -0400, Paul Van Delst wrote:

> Hello there,
>
> A colleague produced a colour X-Y plot for a paper and saved it to a regular old PS file.
> The editor mailed back stating that the file contains RGB colours and could we please
> create the file in CMYK colours.
>
> How does one do this? Using
> DEVICE,/CMYK
> produced exactly the same PS file.
>
> Doing,
> TVLCT,r,g,b,/GET
> CMYK_CONVERT,c,m,y,k,r,g,b,/TO_CMYK
> produced the appropriate c, m, y, and k arrays, but how does one "load" the CMYK arrays to
> be used? Doing
> TVLCT,c,m,y
> produced exactly what I thought would happen - no black.
>
> Any ideas?

Yes.

Try:

DEVICE, /CMYK, /COLOR

You need to put the device into color mode when you select CMYK :-).

Make sure that you do any LOADCT's after the DEVICE call.

You also should not need to put CMYK values in the color table with
TVLCT/CMYK_CONVERT. The PS device should do this for you.

For a program like:

SET_PLOT, 'ps'
DEVICE, /CMYK, /COLOR
LOADCT, 5
n = 50 ; Size of array for Bessel
; Make the Bessel function:
a = BESELJ(SHIFT(DIST(n), n/2, n/2)/2, 0)
TVSCL, DIST(n)
nlev = 8 ; Number of contour levels
; Make the Contour at normalized Z=.6:
CONTOUR, a, /OVERPLOT, ZVALUE=.6, /T3D, $
LEVELS=FINDGEN(nlev)*1.5/nlev-.5, COLOR=1
DEVICE, /CLOSE

you'll see an image in the PS file that uses a COLORTAB and

and is rendered with something like:

{COLORTAB currentfile picstr readhexstring pop 0 get
4 mul 4 getinterval } bind false 4 colorimage

Things like contour lines will have postscript color commands like

1.000 1.000 0.000 0.980 setcmykcolor

Hope this helps,

Karl

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[Message index]

		Re: How to do RGB to CMYK conversion for PS output? By: Paul Van Delst[1] on Thu, 13 July 2006 12:55
		Re: How to do RGB to CMYK conversion for PS output? By: Karl Schultz on Thu, 13 July 2006 12:23
		Re: How to do RGB to CMYK conversion for PS output? By: David Fanning on Thu, 13 July 2006 11:46
		Re: How to do RGB to CMYK conversion for PS output? By: George N. White III on Sat, 15 July 2006 12:31

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