[argyllcms] Dispcal - Inverting Jacobian failed?
- From: "Alastair M. Robinson" <profiling@xxxxxxxxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 21 May 2009 01:31:04 +0100
Hi,
Quick question - what does the error message "Inverting Jacobian failed"
from dispcal mean?
I have a dirt-cheap TFT monitor here whose response I expected to be
pretty funky since there's no direct backlight brightness adjustment.
Instead, the "brightness" control appears to adjust some form of
gamma-like curve, and the "contrast" control... well I'm not sure
exactly what it's doing yet - it looks like it could be scaling the
range about a pivot point that depends on the the brightness control's
setting!
Unsurprisingly it's a challenge to get this monitor operating at a
bearable brightness without causing either clipping in the highlights or
shadows.
Anyhow, my first attempts to calibrate it led to the above mentioned
error being printed in the shell window - once at the beginning of each
pass. What does the error mean?
Despite the error, the resulting calibration looks pretty good. The
only quality issue I see, having performed calibration and profiling, is
a visible transition between white and the lightest visible grey in a
greyscale ramp.
All the best,
--
Alastair M. Robinson
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