Re: Meaning of Brightness for TFT monitors

Results so far:

Thanks for all contributions.

Again about Spectrocam:

If I had to design a digital or analog filter for signal
processing (I had 200 of them in one project) then this
would have almost no overshoot in the step response,
e.g. Butterworth type, overshoot 3%, or a Bessel type.

Here is a screenshot, monitor white:
http://www.fho-emden.de/~hoffmann/spectrowhite.gif

The instrument was always calibrated with the white
reference and for darkness.
Dark noise is typically less than 0.1% of monitor white.

Further specs:
Optical resolution 5nm (used in graphic and data file)
Bandwidth 20nm
Aperture 1.5mm x 2mm
ADC 12 bit

I don't expect accurate measurements for the TFT
by Spectrocam, but I'm still wondering where the
negative values are coming from.
The ADC should deliver unsigned data (not negative
numbers), using a small analog offset which allows
to detect small negative errors in the data acqui-
sition system.

A few comments on the historical background, which
might explain my ranting:

I purchased the ProfilerMaker 5 Publish package
December 2005:
Calibrate Monitor/Camera/Scanner/Printer(any) and
make Device Link.

Wasted one weekend by not being able to install
I1-Match: "not licensed".
This on two computers, parallel: Win98, WinXP.
Updated the Hasp Driver several times.

Gradually it turned out that this package doesn't allow
to activate I1-Match.
One has to use MeasureTool and ProfileMaker.
A CRT could be calibrated, but it was impossible to
verify the results by GMB programs.
I1-Share has a light meter, but this uses a filter cap
instead of the monitor adapter (this program is anyway
garbage).

Results could be verified by X-Rite DTP-92 (of course
not DTP-22, a typo) and Spectrocam.

Then it turned out that one needs two additional
programs:
Display Profile (choose a profile with LUT tables as
system profile and set the LUTs).
Calibration Tester (show content of LUTs and reset
eventually).
These useful programs are somewhere on the CD (not
automatically installed).
Calibration Loader (Autostart or on purpose) is auto-
matically installed but it doesn't work always (Win98
and/or WinXP).

I had a longer conversation by telephone with a Logo
Steinfurt programmer in Germany.
My impression is that they think:
'It is as it is and as it is it is good'
Not much interested in customer's feedback.

The actual state: I have five instruments (two of them
are irrelevant for the monitor though), but I'm not able
to get reliable information about the CCT of the TFT
monitor.

Best regards --Gernot Hoffmann

.

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