Calibration speed issue.

[James Ilya Freeman]

Hi Graeme.

I have contacted you about extremely slow calibration speed in the black
shades in the past.
This speed issue has only began in the last two version, when you have
fixed the lowering of the contrast ratio after calibration.
Are you planing to fix this issue or leave it as is?

Thanks.

James Freeman

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[Ron Suessmann]

Hello,

thank you for your message. Please note, that I´m actually out of office. Your message won´t be forwarded. After my return I will answer soon as I can.



Best regards,
Ron Süßmann

[Graeme Gill]

Post by James Ilya Freeman
Are you planing to fix this issue or leave it as is?

Hi,
well it would be good to fix it, but I'm not really sure how to. I
don't have any examples of this behavior to investigate, since it depends
on the interaction of the calibration algorithm and the particular display.

A possible direction to investigate would be to see if using dithering
in the test patches may speed the iterations up.

You could provide some feedback on this idea if you could try using the
MadTPG as the patch color source, and see if that helps your situation.

See <http://forum.doom9.org/showthread.php?t=146228>

Graeme Gill.

[James Freeman]

I already use madTPG.
I think the problem is in the very low expected dE in the lower black
shades.
If you remember I contacted you about lower than native contrast ratio
after calibration, and you fixed this by lowering the expected
calibration dE in the darker shades.
This fixed the Contrast Ratio but made the calibration time twice as long.
Some times it takes 10 attempts for a single shade of black, other times
it just fails to reach the extremely low expected dE and gives up (in
the log).

If you can, please change the calibration dE behavior to what it was in
version 1.6.0/1 so that calibration will be faster (like it was).
I will just change the 0.000 step to 0.00, 0.00, 0.00 in the .CAL file
to preserve the Contrasts Ratio.

Thanks

Post by Graeme Gill

Post by James Ilya Freeman
Are you planing to fix this issue or leave it as is?

Hi,
well it would be good to fix it, but I'm not really sure how to. I
don't have any examples of this behavior to investigate, since it depends
on the interaction of the calibration algorithm and the particular display.
A possible direction to investigate would be to see if using dithering
in the test patches may speed the iterations up.
You could provide some feedback on this idea if you could try using the
MadTPG as the patch color source, and see if that helps your situation.
See <http://forum.doom9.org/showthread.php?t=146228>
Graeme Gill.

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[Graeme Gill]

Some times it takes 10 attempts for a single shade of black, other times it just fails to
reach the extremely low expected dE and gives up (in the log).

Is that using MadTPG ?

If you can, please change the calibration dE behavior to what it was in version 1.6.0/1 so
that calibration will be faster (like it was).

That's not possible without compromising the black level.

I will just change the 0.000 step to 0.00, 0.00, 0.00 in the .CAL file to preserve the
Contrasts Ratio.

That's fine for you, but not everyone else.

The whole _point_ of calibration is to measure the display,
not make assumptions about it as you are doing with the above
edit of the .cal file.

Graeme Gill.

[James Freeman]

Yes that is with madTPG & i1 Display Pro.
1.6.0/1 did not behave like that, and was very accurate as well (and
faster).

Graeme: "That's not possible without compromising the black level."
Was it compromised in 1.6.1?

If I understand correctly:
When using *dispcal -k0*, step 0 should not be anything BUT 0.0, 0.0, 0.0.
Why would it? I want my native LCD black level, so sending 0,0,0 from
the GPU is most logical no matter what comes in the next steps.

Thanks.

Post by Graeme Gill

Some times it takes 10 attempts for a single shade of black, other times it just fails to
reach the extremely low expected dE and gives up (in the log).

Is that using MadTPG ?

If you can, please change the calibration dE behavior to what it was in version 1.6.0/1 so
that calibration will be faster (like it was).

That's not possible without compromising the black level.

I will just change the 0.000 step to 0.00, 0.00, 0.00 in the .CAL file to preserve the
Contrasts Ratio.

That's fine for you, but not everyone else.
The whole _point_ of calibration is to measure the display,
not make assumptions about it as you are doing with the above
edit of the .cal file.
Graeme Gill.

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