David Thompson wrote:
All consumer ink jet printers are programmed to work from the RBG file format. However, in the end, the printer’s output color gamut is much closer to commercial CMYK gamut than it is to SRGB or Adobe RGB. The best way to avoid a surprise is to use the CMYK preview in Photoshop to check for out-of-Gamut pixels and their nearest in-Gamut CMYK value. You have the option to use color replace where needed to see what it will look like and send a revised RBG file to the printer.
I’m an advocate of using CMYK for color correction, but I have not found what David says to be the case. It is also very easy to set your printer profile as the gamut warning profile, and get a more accurate warning of any out of gamut colors. My prediction is there will be no out of gamut colors, if you work in sRGB, and almost none if you work in Adobe RGB.
The gamut of my Epson 1270 has a larger footprint than SWOP CMYK in all cases, and is somewhere between sRGB and Adobe RGB. The 1270 profile has substantially larger footprinnt than Adobe RGB for L=25% and L=75%. This translates into more color variation in shadow and highlight than. Looking at the 1200, an older model, the gamut is actually somewhat larger.
If you are interested in seeing this for themselves may experiment using the free LabMeter download from curvemeister:
http://www.curvemeister.com/tutorials/LabMeter/ If you create several views of Labmeter, you may assign each of them a different profile, then manipulate the Lightness value for a realtime comparison of all the gamuts with one another.
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Mike Russell
www.curvemeister.com
www.geigy.2y.net