> > Hi Pymol'rs, > > > > I have search the Wiki and Mail-list archive to find a protocul for > > using the CMYK color space, but have only found > "color-safe" definitions. > > > > My Question(s): > > > > When do you define the color space during the creation of a > figure to > > ensure usage of a particular color space, ie. cmyk? Can > this be done > > from a script and with which command, "space cmyk"? > > > > >From my understanding from the mail-list, I need to define > the color > > space before I use any color. Is this correct? Can it > also be done > > retroactively prior to ray tracing? > > > > Finally, once the color space is defined, do all the rgb colors get > > redefined automatically, or does this need to happen manually? I > > found the table for the biggest culprits, but Warren > pointed out there > > was internally defined colors for the atom types. Does > someone have a > > macro that redefines the pymol defined colors including > those for the atoms? > > Chris, > > CMYK is a device-dependent colour space, i.e. the colour that > is chosen to match to a particular RGB colour depends on the > machine it is going to be printed on (and hence the inks that > will be used in the printing). > Therefore there is no one-to-one mapping of CMYK values to > RGB values (even with a profile defining how the RGB values > should be displayed). > > Since pymol's idea of CMYK is so limited (and from a > printer's point of view probably shouldn't even exist) you > are far better off getting the RGB image out of pymol to look > just the way you want it to (assuming a calibrated display > and approprate colour profile) and then use a full-featured > converter to generate the appropriate CMYK image for the > device it is going to be printed on. One suggestion for a > converter is GIMP (soon to be renamed something else) because > it does know how to use/respect ICC profiles. >
Hold on -- from the end-user's standpoint, the only thing that matters is: "does the image I see on the screen match what comes out of the printer". Who cares about the "printer's point of view"?! In the real world, scientists do not have time or resources to mess with color profiles and color-calibrated hardware. They simply want to go from screen to hardcopy knowing their colors will not be grossly distorted by their hardware, which is often consumer-grade, non-calibrated equipment. Though CMYK is indeed device-dependent, there are some color regions that, *in practice*, are more problematic than others when printing from an RGB source. If you stick to safer regions of RGB space that are pragmatically captured through PyMOL's "CMYK" space command, then you will get closer to a WYSIWYG experience even in the absense of calibration. On the other hand, blithely working in RGB space and then relying upon automatic RGB->CMYK color translations in the *absense* of color calibration for both display and printer almost always results in unacceptably poor color quality, and that is the practical real-world issue facing PyMOL users. So I would recast your advice as follows: Unless you have calibrated hardware for both display and printer, you are definitely not "far better off getting the RGB image out of pymol to look just the way you want it to". Instead, you are far better off avoiding areas of RGB color space that are difficult or impossible to handle without professional-grade color hardware, and that is the sole task PyMOL's CMYK capability is designed to help you with. Cheers, Warren -- Warren L. DeLano, Ph.D. Principal Scientist . DeLano Scientific LLC . 400 Oyster Point Blvd., Suite 213 . South San Francisco, CA 94080 USA . Biz:(650)-872-0942 Tech:(650)-872-0834 . Fax:(650)-872-0273 Cell:(650)-346-1154 . mailto:war...@delsci.com
