CHROMiX

CTP CMYK Dot Gain Info Different from that of MeasureTool

Hi, I kind of keep adding, but I just found some problems or just curiosities
in ColorThink Pro. When I open a CMYK profile in the Profile Inspector, we
can see the dot gain info of it. But I see the info of the same profile is quite
different from that of X-Rite MeasureTool. Some ink is higher, some lower.
How can it be different when it is from the same profile?

Also I found the dot gain values of US Sheetfed Coated profile is way too
high. All inks are higher than 23%. I don’t think it is correct. It should be
somewhere between 13% and 22%.

And in addition, in the Profile Inspector, dot gain input % is misleading. On
the bottom it says 75% but in the right it says 25%. Which is right?

I believe that the dot gain info in Colorthink is based on XYZ (colorimetric)data compared to Measuretool basing the dotgain on density (derived from Spectral measurement data). Based on the different calculations, you’ll likely notice a difference between the two.

Also keep in mind that Measuretool’s dot area/gain plots are using DIN filtration rather that Status T used in the US. This will make a diffference mainly in the yellow, showing slightly higher gains compared to status T.

As far as the US Sheetfed Coated profile goes, it was derived from a 3M Matchprint on Commercial base rather than an actual press run. That, and the XYZ calculation might be skewing the dot gain results from what you expect fot a sheetfed profile.

Not sure I understand…are you referring to the reported dotgain at 75%…input is 75%, but dot gain is reporting 25% on the right? Looks ok on my end.

Good points here.

Measure Tool and ColorThink do indeed calculate dot gain differently. Measure tool uses the measurement data that is embedded in the profile (the measurement tag), and ColorThink uses the profile to “back-calculate” the measurement data through the profile. We chose this method explicitly to provide people a means to get this dot gain data from profiles that don’t have embedded measurement tags.

I would second Mike’s assessment of what’s probably happening with the US Sheetfed Coated profile. I’d say he’s right on there.

I understand what you are seeing with the dot gain labels. The label across the bottom that says 75% is listed on the right upper right column (“input”) readout as 25%. The upper right number is wrong, and should be 75% to correspond to the bottom figure. This is a bug and we’ll fix it. In the meantime, follow the bottom labels. They are correct.