VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Tue Oct 30 2007 - 17:49:30 CDT

Adrian,
  Color space conversion is generally not done internally in
rendering packages. Most renderers do their work in linear
gamma RGB color space because that maps directly to the physics
of lighting. The main issue with color space conversions from
linear gamma RGB to CMYK and the like is that most of the CMYK
and other printing oriented color spaces have "holes" or
other discontinuities, that result in some of the original
RGB colors being clustered together, rounded to another color,
or clamped at the edge of the representable color space.

What this means for you and anyone else that needs to do this
kind of conversion is that you'll need to choose the original
VMD colors you're using for your figures carefully so that they
don't result in RGB renderings that go way outside the CMYK gamut
that you plan to convert to. Photoshop etc will do the color space
conversion for you, but it won't help you prevent damage to your
figure caused by the reduction in the gamut of the final color
space, and this is best done by making a few "practice" figures
using the colors you like, and adjusting the RGB renderings so
that after conversion you get acceptable output. The worst part
of all of this is that two different printers will treat the same
CMYK input differently as they will have variations in their actual
color gamut versus the input color space (again, another conversion....)

I hope that helps, even though nothing about it is easy...

Cheers,
  John Stone
  vmd_at_ks.uiuc.edu

On Tue, Oct 30, 2007 at 05:08:37PM -0400, Adrian Roitberg wrote:
> Dear All,
>
> The Journal Proteins:SFB requires figures in TIF format, CMYK color scheme.
>
> Does anyone know how to do this from vmd, besides writing a povray or
> similar file, creating a tiff, reading into pjotoshop and changing to CMYK
> ?
>
> Thanks !
>
> --
> Dr. Adrian E. Roitberg
> Associate Professor
> Quantum Theory Project and Department of Chemistry
>
> University of Florida PHONE 352 392-6972
> P.O. Box 118435 FAX 352 392-8722
> Gainesville, FL 32611-8435 Email adrian_at_qtp.ufl.edu
> ============================================================================
>
> To announce that there must be no criticism of the president,
> or that we are to stand by the president right or wrong,
> is not only unpatriotic and servile, but is morally treasonable
> to the American public."
> -- Theodore Roosevelt 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
Email: johns_at_ks.uiuc.edu                 Phone: 217-244-3349
  WWW: http://www.ks.uiuc.edu/~johns/      Fax: 217-244-6078