[argyllcms] Re: Can anyone help with a weird OSX problem?

  • From: Florian Höch <lists+argyllcms@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 27 Jul 2014 13:43:25 +0200

Am 27.07.2014 um 07:58 schrieb Quartz:
> http://www.sneakertech.com/-/displayxyzlut.zip
> This is an XYZ LUT with a swapped matrix, native white point, and the 
> cinema display correction matrix borrowed from iColor Display.
> The only setting that's non-default is that, like the last profile, I 
> have to set a target luminance of slightly less than what the display is 
> capable of in order to avoid subtle rainbow stripes in the near-whites 
> (this display acts slightly weird at the top of its range). FWIW, with 
> the correction matrix active, the white level is reported as being quite 
> a bit lower [~92] than without [~101].

Ok. This time around, the calibration curves meet near white, which is
more in line with my expectation when using native whitepoint.

> As far as my problem goes.... the result is mixed. The 3D graph still 
> shows the blue primary as being offset. Within Photoshop, AdobeRGB and 
> sRGB "blue" come out as 89,41,255. Not quite as purple, but still not great.

It would be interesting to know what that color measures as. I've
attached a small testchart so you can easily do this. Do the following:

- Make sure the last profile you attached is installed & active.
- In Photoshop, create a new sRGB document. Fill it with white.
- Drag the attached file to the dispcalGUI main window. It should show
up under "Testchart".
- Select "Untethered" under "Display".
- Make sure the generic Apple Cinema Display wLED correction is selected.
- In the "Options" menu, choose "Measure testchart".
- In the window that pops up, disable the "Auto" checkbox.
- Position the i1D2 over the Photoshop document area.
- Click "Measure".
- Fill the Photoshop document with blue (RGB 0 0 255).
- Click "Measure".

Post the measured L*a*b* values for white and blue.
According to the profile the blue should read close to L*a*b* 42 42 -93.

> What's my next step? Should I mess with the colormetric/perceptual 
> setting next, or something else?

Worth a try. Click the "Advanced" button next to "Profile type". Source
profile should be sRGB.icm. Tick the "Gamut mapping for perceptual
intent" checkbox and set it to "Perceptual". Leave the rest of the
settings unchanged.
In the "Options" menu, choose "Create profile from measurement data" and
select your existing XYZLUT profile.

Note that to use the perceptual mapping that was generated, you have to
select perceptual intent. Not all applications allow this, but Photoshop
does via a custom softproof: Under "View" -> "Softproof" - "Custom",
select your newly created display profile. Make sure "Use RGB numbers"
is unchecked. Set rendering intent to perceptual.

Florian Höch

ORIGINATOR "Argyll targen"
CREATED "Sun Jul 27 12:30:38 2014"
APPROX_WHITE_POINT "95.106486 100.000000 108.844025"
DESCRIPTOR "Argyll Calibration Target chart information 1"


1 100.000 100.000 100.000 95.1065 100.000 108.844
2 34.5269 16.1390 100.000 23.6501 11.7844 95.5793

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