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Following BT.2408 the reference white for PQ HDR has been changed to 203 nits. HCFR should follow that, and change it from its current value of around 50% value to the about 58% value.

See Chapter 2.1 in here:
https://www.itu.int/pub/R-REP-BT.2408-4-2021

Since the value of 203nits is given in table 1 (page 6) for both PQ and HLG we can assume that 203 is an exact value. From this it follows that the value of 58% is approximated and should be exactly 0.580688881.

The two values that will need to be changed are:

• 94.37844 which is the luminosity of the reference white in nits, this will need to go to 203
• 0.5022283 which is the percentage of the maximum value, this will need to go to something like 0.580688881.

This change should also be reflected in the generator, where for example the primaries and secondaries, as well as the saturations should ask for that 58% luminosity instead of the current value of 50%.

OS: Windows 11
Meter: Calibrite Colorchecker Display Plus
Driver: Default Windows

I have a new colorimeter which is detected and works correctly with the Calibrite Profiler software, but in HCFR when creating a new project I get a "Starting communications with meter failed" error. The meter is not visible in the meter selection drop down.

I briefly looked into getting up and running with ArgyllCMS driver, however I didn't proceed once I found on the HCFR Wiki that the Colormunki meters (which I understand this line of Colorimeter to be derived from) should be supported with the standard Windows Driver. I also didn't find a lot exploring this issue with this particular meter.

Hi there

I was trying to create a colorimeter correction matrix using an unsupported spectrometer. The resulting matrix ends up to be incorrect. Workaround is manually creating a reading and using it as a reference.

Please see this post and following messages for details: https://www.avsforum.com/threads/hcfr-open-source-projector-and-display-calibration-software.1393853/post-61857342

Thanks!

Can you consider add the CIE 170 standard in the future?
Calman home added this CIE standard, and displaycal and hcfr have not been updated for a long time and failed to have this standard.

BT.2408 sets the same reference white level for both PQ and HLG at 203 nits. This equals about 58% for PQ and around 75% for HLG. Currently HCFR does not take into account any the reference white level for HLG and sets the expected brightness to 100% which is much too high. The implementation should be just like for PQ, with just another level of 75%.

See Chapter 2.1 in here:
https://www.itu.int/pub/R-REP-BT.2408-4-2021

Since the value of 203nits is given for both PQ and HLG (table 1 on page 6) we can assume that this value is exact. From this it follows that the value of 75% is approximated and should be exactly 0.749877365.