Illuminant and Observer Choice when reading linearization charts


Hello my dear alternative people,

I am currently using my i1Pro 2 spectrophotometer to read and linearize some targets.

I have both ColorPort and the i12 software, but for some reason the i12 software does not seem able to read the reference files of the corresponding charts (it looks for files with the extension .txt or .rmxf, when the files which come with PiezoDN are .pwxf ? ). Not sure whether I am doing it right.

Anyway, it seems with Colorport things are easier, and maybe you recommend using this software over the newer i1 Profiler?

With Colorport, I am having a few questions that I am sure you will know:

  • Do you measure by bands or spot by spot? Which solution will give better results?

  • I suppose that by default the spectrophotometer is reading in tungsten mode (not UV mode) right?

  • When exporting the measurements, I choose “Tab delimitated”, No conversion (XRGA) and then I only select Lab values. Is this correct?

  • The main question comes when I have to choose the Illuminant and the Observer values. I have seen that the Lab* values change slightly when I select different options for the Illuminant and the Observer. Which are the values we should choose? (I attach the different options here… in french, but it is self-explanatory since very similar to English)

  • I am using Calc software for Mac, from Apache (Open source) which is right like Excel and free. It cannot save as txt, so what I suppose I should do is to copy the CGATS tab and paste it into TextEdit, and then save it as a txt file, right?

Thanks so much for your help!

Warm regards,



All of these are correct. They are the defaults for reading printed patches on paper.





Fantastic, thanks Walker. So then Illuminant=A and Observer=2 is the base and default values I should use…


Otherwise, are you measuring the targets by bands, or patch by patch with the i1profiler? Is the measurement by band less accurate than going patch by patch based on your experience? I know you use i1profiler too…


Always go patch by patch with PiezoDN!