It's sad to see Gimp giving in to the CMYK myth. I suppose it was simply too difficult to educate all the users who were somehow convinced of the need to work i

It's sad to see Gimp giving in to the CMYK myth. I suppose it was simply too difficult to educate all the users who were somehow convinced of the need to work in CMYK space. Some of us remember when Microsoft Word document formatting would get all messed up if you moved the document to a computer with a different model of printer. The trouble was that documents were expressed in terms of specific printing hardware. Using CMYK has a very similar problem. You can't get a generic CMYK that just magically works directly on every printer, and even if such a thing existed you still wouldn't be able to see it on your screen. The black is also a problem; a 4-color space is overspecified. You'd really need CMY. The actual CMYK needed is only known to the printer driver or even just internal to the printer. You'll need to convert. Since you are converting anyway, there is no need to start from a color space as awkward as CMYK. There are really just two things of use beyond RGB, gamut mapping/alerting and spot colors. Gamut mapping distorts your color space to fit the output device. Alerting is an alternative, for example by making out-of-gamut colors flash on the screen to tell you that they are not going to be printed correctly. Both of these are deeply problematic, because they require knowledge of the specific printer that will be used. That includes the paper color, the ink currently installed, the hardware model, the driver, and maybe even the intended viewing light. Spot colors are for crazy kinds of ink that need to be handled separately. The ink might have sparkles, UV fluorescence, magnetism, and so on. These kinds of inks don't normally get treated as part of the colorspace. They shouldn't be affected by operations like adjusting saturation. The way these inks are displayed on the screen may be quite unrelated to how they actually look. You should be able to configure an on-screen appearance with any desired color or filter effect or even with flashing.