Retrieve original measurements from ti3 file

[royb]

Hello all,

I am using a non-standard observer for profiling (1964_10 and at 6500K). After profiling, the measurement ti3 file has the XYZ values in 1931_2 (using i1 Pro). What I want is to get back my original measurements that were done using the 1964_10 observer. I am looking for the matrix that DisplayCal has applied to convert the original measurements to the 1931_2 observer. Where can I find this transformation matrix (there is no CHAD matrix in DisplayCal profiles)?

Thanks in advance!

Roy

[Vincent]

Redo readings with ArgyllCMS saving spectral data (and XYZ if you wish). Then you can compute color coordinates using the observer you want.

[royb]

Hello Vincent!
Thanks for your reply. As I said, I have i1 for the measurements and I cannot save spectral data with it. I there a way I can transform the .ti3 XYZ (D50/2) to XYZ (D65/10)?

[Vincent]

If you have an i1pro spectro… you can get spectral data, it is the actual output of measurement. You need it for what you ask.

[royb]

Hi Vincent!
Thanks for replying. Yes I understand that reversing the spectra is one way of doing this, but isn’t an ICC profile supposed to provide a way to reverse the D50/2 colorimetry to original colorimetry using the CHAD tag? I think this tag is missing in Argyll profiles, and that we should use the ARTS tag. What I don’t know is how to convert the ARTS tag value to a floating number matrix.

[Vincent]

That is chromatic adaptation, usually meant to deal with DeviceA<->PCS<->ColorspaceB transformations, not transforming measures from one observer to another.

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