Alan Smithee writes …
I don’t get why "the literature" all says inkjet printers are RGB devices.
There are several answers to this question, and my take on it is somewhat different from Bill’s or Tacit’s. For one, I see no quality issue with printing a CMYK image on an inkjet. The extra trip to RGB space is not a significant problem, IMHO.
The main reason that printers are RGB devices is that this is the interface provided by the operating system, Mac, Windows, SUN, and others. Therefore all printer manufacturers provide RGB drivers for their devices.
For inkjets, the RGB driver converts the RGB values to the actual dots of ink that go on the page, and part of this conversion is translating RGB to CMY, CMYK, or CcMmYK.
When you print a CMYK image from Photoshop, here’s what happens.
1) the image is converted from CMYK to RGB (in photoshop, not the driver) using the specifications you provided in your Printer Setup aka Print Preview.
2) the driver converts the RGB data to dots.
But there’s way to look at your question. CMYK is really RGB in disguise. Inks work by absobing part of light reflected from the paper. Cyan absorbs red, magenta absorbs green, and yellow absorbs blue. So red will print as a mixture of magenta and yellow, and other colors are translated in a similar way
Also, there are ways to print directly in CMYK, using postscript.
If you want to experiment with using CMYK in Photoshop, go ahead. You’ll see some reduced saturation in certain blue colors, but for most images this is not a big deal, and there are ways to deal with this. —
Mike Russell
www.curvemeister.com