Hi Ezio, Rodney. Ezio wrote: > For RGB printers (and more for other color rendering technologies) this > limitation is not any more valid. > What I have understood , please correct me if I am wrong or saying no-sense, > is : > RGB printers 3, 5 , any number of inks ... can combine the colors in a way > that is not achievable (by some extension) by the phosphores of the screen. I find it very difficult to believe that any reflective and subtractive output can achieve colour of greater gamut than a self luminous additive system. I've measured my monitor as having a 600:1 brightness range, a good paper print has what? 200:1? This means that the saturation of the printed version would need to be over 3 times greater than the screen to overtake its gamut. I accept that the CMY inks may not be the exact complement of the RGB phosphor colours, but this is a problem of hue shift, not saturation. Then Andrew Rodney wrote: > > Then on page > > 113 of *Information Visualization* is a color gamut chart that shows the > > monitor gamut far exceeding the gamut of printed inks and the gamut of > > printed inks entirely within the gamut of the monitor > > I don't buy that! There are greens and cyan's in a CMYK SWOP like gaumt that > fall outside monitor gamut. A monitor can't display a pure cyan. In the > enclosed gamut map you cans see that the TR001 SWOP profile has areas that > fall outside ColorMatch RGB....... snip. A small shift in the green phosphor would eliminate the discrepancy, but the comparison between reflective and self-luminous colour spaces is problematic in any case. You only have to hold printed material side-by-side with a monitor for that to be self-evident. I'd be much more concerned about the SWOP inks not being able to reproduce a decent blue than any slight discrepency between Cyan renderings. As corroborative evidence, I found very little problem in getting a good visual match for the Epson 1270 inks on photo glossy paper into an sRGB colour space. The red actually gave the most trouble. I've pasted those colour patches back into the SWOP v ColourMatch chart. (see attached) The Epson 1270 is reckoned by many people to give one of the best outputs you can obtain with inks, so I would have thought that matching it's gamut would be a good test of any RGB space. The difficulty with placing ink colours on a conventional u/v diagram is that they aren't 'pure' colours, and so don't have a true locus in the colour space shown. IMHO the SWOP colour diagram is a 'cheat'. It seems to me as if the publishers of that chart have some vested interest in making RGB spaces look bad. Are they half-tone ink manufacturers by any chance? Afraid that web publishing might damage their business? Regards, Pete.
