Proper color workflow with CMYK inkjet printer

Question

Hi, I work in an academic science group that has a networked HP DesignJet 800ps printer (postscript RIP). Unlike many inkjets, it appears to be a true CMYK printer - that is, our i1 Match software recognizes it as a CMYK device. We do all our printing in house - we don't have to worry about commercial printing or publishing, and our color management needs are basically confined to trying to have the printer's output match what we see on our monitors when we print photos in Photoshop or posters in Illustrator.
Having previously worked only with RGB printers and in Photoshop, I am pretty much lost now as to how to set up our color management workflow. (And don't even ask about my colleagues. :-)) I've never had to worry about either CMYK workspaces or printers before. I want to keep things as simple as possible for the staff here, given that none, including myself, are graphics specialists.
I've looked at the "Color Workflows for Adobe Creative Suite 3" document published by Adobe, and although it is very meticulous, none of the examples seem to match our situation. Specifically, all the info regarding CMYK printing involves working with commercial presses, which is not relevant to us.
I would like to avoid making my colleagues work in different color spaces depending on whether they are working in Illustrator or Photoshop - ideally, I would like it if we could stay in RGB at all times. First question: Is this unrealistic given that we have a CMYK printer?
No doubt I will have more questions, but I want to start simple for now. Thanks for helping me out - this is not my area of expertise.

Answer 1

> profile them as RGB devices" (to quote the book). The printers that I've profiled in the past with i1 worked this way.
As Peter points out in his post, it is most likely that your RIP is a CMYK RIP (most RIP's are.) If that is the case, you'll be profiling a CMYK device, not an RGB device (as you have in the past.) It is a totally different exercise to profile a CMYK device - ink limits and Kgen are variables that must be dealt with.
> Yes, details would be very helpful. Thanks.
Color management is all about moving from one device/color space to another device/color space while maintaining color appearance as closely as possible.
1) Based on the description of your workflow, step one is to create your original art in a well-behaved RGB color space (like Adobe98) while viewing it on a well-calibrated monitor.
2) If your final output is to be on the HP 800ps, step two would be to preview that art on your monitor as it would look on the HP. This is called soft-proofing - a process by which the art is viewed through the HP profile on-screeen so you can see what happens to all those beautiful, rich RGB colors when they're squeezed into the smaller gamut of the HP profile.
To do this, you go to View > Proof Set-Up > Custom, and choose the HP 800ps profile from the pop-up of all the profiles on your system. You can also choose from among 4 rendering intents - Relative Colorimetric, Perceptual, Absolute Colorimetric, and Saturation. Choosing the correct rendering intent is key - this willl determine how Photoshop deals with the out-of-gamut colors. Without getting into an explanation of what each RI does, the important thing is to choose the one that LOOKS the best on screen. There's no magic to it. In general, for photographic images, you'll be choosing from Relative or Perceptual. For vector graphics (which it sounds like you're doing), throw Saturation into the mix as well. Just try them and see which looks best.
Additionally, be sure to check "Black Point Compensation."
This will give you a good idea of what the final printed version will look like. While you're in soft-proof mode, you can edit the RGB file to alter the way out-of-gamut colors appear. In fact, there's no reason why you couldn't create your art from the beginning while in soft-proof mode. Using a well-built profile and a good calibrated monitor, you should be able to get an extremely close match between monitor and print.
3) When you print, be sure to choose the same profile/rendering intent that you used in Proof Setup.
Again, it all starts with a good profile. Good luck.