Hello Marco Allow my comment here, because I recently stumbled across the very same problem. The quick answer is that there's no "clean" way to do it yet, also I was asking kindly to support some option in targen to add custom CMYK (or RGB) patches taken maybe from an external list file - you may verify that in some message of mine one month or so ago. To achieve that - but note that I'm very unsure on the effectiveness of adding custom patches - I had to write some very dirty custom code to batch estimate (by 4D interpolation) the XYZ value of a CMYK patch from those limit values already present in a fresh .ti1 file [sorry my stuff is not portable and won't run on your machine] Those XYZ values are a first aid to check during chart readings against possible reading errors or line mismatch. They're estimations the first time, of course. I understood that Graeme is preferring this standard approach: -print a testchart with randomly spreaded points (they should better cover, statistically, the device gamut and avoiding resonances) -measure, generate a first profile, then generate a second testchart passing the previous profile to targen so it will be able to better place the test patches in device space (see targen options) -iterate if needed Expecially when working with CMYK, I suspect that it's not so trivial and intuitive to select problematic patches to add at will in order to improve results, there're too many combinations involved. It should be (imho) colprof itself to possibly suggest ranges of CMYK combinations needing a better exploration. But it's not the case yet. /& > Hi all > I'm new to color management and color stuff in general. > I'm trying to generate a custom CMYK tif target test chart with values that > I consider problematic for my printing system. > I think that I could edit the ti1 file because automatic choosen values > doesn't fit my needs > and give them to printtarg but I faced the issue of XYZ values in the ti1 > file. > I think I could remove them but I got a > printtarg: Error - Input 'pro2.ti1' file doesn't contain field XYZ_X in > first table > what is the purpose of XYZ values in a target file ? can I fake them > probably not and if no why? > thanks in advice.