-----Original Message----- From: "Asman, Andrew J" <Andrew.Asman@xxxxxxx> To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx> Date: Fri, 30 Jan 2009 15:45:41 -0500 > ...I usually modify the color values on the patches to include significantly > more pure colors because I am predominantly measuring a printers ability to > uniformly print pure colors (CMYK) on a page. But nevertheless, use You enough in-gamut patches to profile a scanner? May be Your profiles are exact only on a gamut boundary of a particular printer? > ...For example, if I create a profile using pages from a printer and then use > the ICC profile to measure pages that were printed on the same printer, the > average delta E value when compared to the Gretag Spectrolino is consistently > under 2. This is very good result. What scanner do You use? Generally it's quite hard to achieve dE76 less than 5.8. > However, if I measure pages using a printer that has a larger gamut than the > one used to create the profile, then the out-of-gamut colors tend to produce > extremely large max delta E value ranging anywhere up to 100 depending on the > printers used. What about in-gamut colors? Under 2dE? :))) > Is there any way to increase the accuracy of the profile when faced with > out-of-gamut colors? IMHO the way is the matrix+gamma scanner profile, because the LUT and even the shaper profiles can't predict out-of-gamut colors anyway. But the gamma can. The in-gamut and gamut boundary dE may get significant worse, but out-of-gamut colors must get significant better. > When I create the profile from a ti3 file I generally use the following > command: > colprof -v -qh -u -al <base_name> colprof -v -qu -u -ag <base_name> I suppose.