Originally Posted by madshi
I've simply used the default HCFR settings and then the 3 tabs "Gamma", "RGB Levels" and "CIE Diagram". I'm far from a calibration expert. How can I create those L* error plot etc measurements you mentioned with HCFR?
Sure, I understand, but I can't help you much with HCFR, since it's not something I use. My comments were partly in relation to opportunities to improve HCFR for those in a position to influence it, and mostly to say that it's not really possible for me to make a judgement about how well the profiling process has worked in your situation from such results.
You're saying you could quickly find out what the problem is, by looking at the files and doing some quick measurements. Maybe you can guide me through it, if it's not too much work? That is, if you think this might be a bug in Argyll that is worth looking at. I can't really judge if it is...
OK, here's how I'd check what's going on with the transfer curve:
[and a note for those following along, ArgyllCMS is a color management toolkit, so it is ideal for tackling unanticipated tasks. But there is no special Video "figure out what's wrong with my color" button, because that's very task specific. And this type of thing is necessary mostly because all this is still under development and verification, it's not something that should normally be needed.]
Grab the latest copy of the experimental tools, since I've made some changes to make the following processes simplier than they otherwise would be.http://www.argyllcms.com/Win32_collink_3dlut_ex.zip
I'll show as examples the output of running these checks on my display.First check
- check if the 75% neutral axis output really has a significant error:
Run the link command again with the same options you used/are testing (to a dummy output file), with the -v flag (verbose output).
Capture the BT.1886 verbose information output, e.g.:
In 75.0% -> XYZ in 0.563522 -> bt.1886 0.536329, log/log 2.166, Lab 78.247177 -0.000040 0.000035
Run dispwin through the video display system to display a 75% patch:
Check that the 3dLUT being checked is in place in MadVR settings and any calibration curves are properly in place.
dispwin -dmadvr -m
You advance each patch by hitting return.
Stop at the white patch for the moment.
In a different window run:
and also set -y whatever or -X whatever to match your calibration/profiling setup
Take the white reference reading
Take another reading in the same spot and check that you get close to Lab 100, 0, 0
Hit return on the dispwin window to advance the patch to 75% grey.
Take a reading of 75% grey, and grab the 75% results, e.g.:
Result is XYZ: 51.252248 53.137075 43.809343, D50 Lab: 77.955860 0.046051 0.028869
Check it against the collink verbose output for 75% above.
So a delta E of about 0.244 - not bad considering my display is not very uniform, and I did the calibration and profile some weeks ago.Second Check
If there is a significant error, then start to figure out why it is occurring.
Lookup what 75% input is being translated to by the 3dLut:
xicclu -et -Et 3dlut.icm
0.750000 0.750000 0.750000 [RGB] -> Lut -> 0.768942 0.769324 0.767517 [RGB]
(I'll assume that you have used calibration curves.)
If you used -a to combine the calibration curves with the 3dlut, then undo the calibration curves of the above 3dlut output to return the calibrated device rather than raw device values:
xicclu -fb display.cal
0.768942 0.769324 0.767517 [RGB] -> 0.758770 0.750586 0.764098 [RGB]
If you didn't use -a because you used -H or you manually installed thecalibration curves using "dispwin display.cal", then the 3dLut output will be calibrated device values.
Lookup what the profile predicts for the display calibrate device values:
xicclu -ff -ir -pl display.icm
0.768942 0.769324 0.767517 [RGB] -> Lut -> 78.298016 -0.035602 -0.149678 [Lab]
Which is very close to the target value for 75% of Lab 78.247177 -0.000040 0.000035.Third Check
Check that the 3dLut output values result in the target color.
Translate the 75% calibrated device values to raw device values:
xicclu -ff display.cal
0.768942 0.769324 0.767517 [RGB] -> 0.778055 0.785218 0.770643 [RGB]
Feed that value to dispwin in native output mode:
dispwin -dmadvr -C 1,1,1 -C 0.778055,0.785218,0.770643 -n -m
and measure the result using white point relative:
Result is XYZ: 50.852465 52.746204 43.123070, D50 Lab: 77.724916 -0.014366 .480866
which is very close to what we measured through the 3dLut and calibration curves in the first check.