RGB to CMYK and Pantone stuff

[BobShrader]

One more clarification on RGB color model, (which really doesn't address the original question asked here, but for your information…)

Red, green and blue are the primary ADDITIVE colors and are based on reflected light. The colors on the screens of television receivers and computer monitors are RGB colors.

Equal amounts of red, green and blue produce white. No color produces black. Equal amounts of red and blue produce magenta. Equal amounts of green and blue produce cyan. Equal amounts of red and green produce yellow. All the other colors seen on these media are created by a combination of various amounts of RGB, the primary additive colors. Limitations on the number of colors that can be produced in RGB come from the medium of production, not the RGB model itself. Computer screens produce better color than television screens. The new HDTV receivers will produce better color than conventional television screens.

Printing and painting, on the other hand, are based on mixing the primary subtractive colors -- the CMY(K) model.

[Sean Sedwards]

Given that Xara have done the work and paid the licence fee, I wish they'd include a lot more information about Pantone in the help file. Specifically, I'd like them to explain the new "Solid to Process" colours which have displaced the old spot colours.

As Gary has already pointed out, a spot (or solid) colour is a single ink that has its own printing plate. The CMYK or RGB values that Xara uses are merely interpretations to help you reproduce the same colour on screen and using other processes. Xara used to use a set of CMYK values that were common to other leading apps, such as DRAW and PhotoShop, but now uses a different set which, on the basis of just a few comparisons, seem to use less coloured and more black ink.

The colour of a true Pantone spot colour is defined by the ink supplier, so the CMYK values that Xara uses on-screen are pretty much irrelevant because those inks aren't involved. Hence, I can see the logic of replacing the old spot colours, which only had to have accurate names to be perfectly matched by the printer, with colours that better translate to the CMYK process. My best guess is that they are derived from Pantone's "Pro-Sim" colours, which are specifically designed for this purpose, however one problem with this theory is that PhotoShop also uses Pro-Sim colours but sticks to the old CMYK values.

Regards - Sean