[argyllcms] Re: Monitor calibration

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 22 Apr 2010 00:33:16 +1000

Simon ANTIBES wrote:

I use XP 32 DispCalGUI +Argyll 1.1.1 +Spyder3 + Dell 2709W Wide Gamut +Nvidia 8800 GTS 512
Now the questions for Photoshop display ONLY :

  - Assuming 8-bit LUTs in
 monitor and graphics card, and not-so-bad monitor,
is it better to calibrate AND profile, each missing RGB LUT value resulting in 256x256 missing colors

I'm not sure what you mean by this.

is it better to set monitor as "standard" reset to factory, graphics card LUT linear, and ONLY profile.

Assuming you are only interested in viewing though a profiled application,
the you will lose less precision though an 8 bit path by leaving the
calibration linear, and using just profiling. Of course this assumes
that the characteristic of the monitor are reasonable, and that the
CMM/profile combination doesn't have to do anything too extreme
to get to the intended colors.

Note that it's fine to use built in monitor controls to adjust
things as long as they don't operate by manipulating the
8 bit data path. (How you can figure this out if the monitor
manufacturer doesn't tell you, I don't know).

- What procedure can I use to compare the two versions - what value is representative ?

Hard to say. Fine, very smooth (ie. low noise) graduations show
things the best. Note that by default Photoshop adds dithering/noise
to it's gradients to suppress stepping artefacts.

Difference with ICC v2 / ICC v4 ?

You won't get V4 out of Argyll.

  - I
get "Effective LUT entry depth seems to be 12 bits" ; does it mean my graphics card supports 12-bit input ?

It would seem that way, although this isn't common with LCD displays,
due to the DVI limitations. The test isn't perfectly accurate, either.
(Are you using DisplayPort ?).

The DELL website information is very poor. No mention of
bit depth, adjustments, anything. It claims "1.07 billion colors",
which equates to 10 bits per channel (1024^3).

[I get 10 bits on my display, but that's because it's an
analog connection to a CRT. ]

Any software using this capability ?

Note that this the output of the VideoLUTs. The inputs are
presumably still 8 bits.

Graeme Gill.

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