[argyllcms] Re: i1 Display bundled with Samsung XL20
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 06 Apr 2009 03:02:50 +0200
Kurt Roeckx wrote:
> On Sun, Apr 05, 2009 at 10:58:37PM +0200, Gerhard Fuernkranz wrote:
>> Graeme Gill wrote:
>>>> Display, or whether the eeprom possibly contains a calibration matrix
>>>> especially tuned for the LED light source of the XL20? (there is at
>>>> least a big inscription "LED SyncMaster" on the body of the i1)
>>>> [...]
>>>> expected). Does somebody happen to know, whether this is a "regular" i1
>>> My guess from an engineering point of view would be that it contains
>>> a standard calibration, and that any special adjustment done to suite
>>> the display would be in the software that accompanies it,
>> My XL20 was unfortunately ligering around for a while (while I was busy
>> meeting other obligations), but now I found a little bit of time to dig
>> it out again and to do a few experiments. I'ts now also the first time I
>> got the "Natural Color Expert" working under Windows XP [last time when
>> I tried (on a different PC), the NCE did not find the monitor - I guess
>> it was an issue with the graphics card, when accesing the I2C bus]. So I
>> had the opportunity now to compare the measurements from NCE with
>> measurements from Argyll, and they are virtually identical [within less
>> than +/- 0.0005 chromaticity units (NCE only reports 3 decimal digits)].
>> This obviously implies that very likely my "LED Syncmaster i1 Display"
>> does not contain the standard LCD calibration, but rather an LCD
>> calibration matrix for the XL20, and it's obviously not the NCE, which
>> performs any special adjustments for the XL20.
>
> I'm not sure how you got to that conclusion. You measured
> something with NCE and with Argyll and they agreed? And from that
> you somehow conclude something?
Argyll uses the correction matrix stored in the instrument's eeprom. If
the NCE readings agree with the Argyll ones, then I conclude that NCE
uses the same correction matrix from the instrument's eeprom as well,
and does not apply any additional corrections. So if there is a special
instrument calibration for the LED backlight in the play, then it is
obviously stored in the instrument's eeprom instead of the standard LCD
calibration.
Btw, I calibrated a few other (non-XL20) LCD displays with this
instrument, and subjectively I find them all a little bit too
red-ish/magenta-ish. And if I compare a notebook display and the XL20
(both calibrated to D65, using the Syncmaster i1 Display) side by side,
then the whitepoint hues don't match visually, but they look pretty
different (I guess, the difference must be several delta E), which
reinforces my suspicion that this instrument requires a different
calibration for measuring a regular LCD than for measuring the XL20.
>> I was also surprised about NCE's calibration procedure. First (as
>> expected) it displays a white patch and one can see that it adjusts the
>> backlight to meet the selected white point target, but then it measures
>> only the three primaries and black (black is likely adjusted too,
>> according to the selected black target; but I had selected "mininum", so
>> I did not notice any change of the displayed black patch). However, in
>> order to establish the calibration, NCE does NOT measure a gray ramp, as
>> dispcal does. And eventually [as I was afraid after this observation],
>> when I ran dispcal on the NCE-calibrated XL20 it turned out that the
>> in-monitor calibration established by NCE is not perfect, it does not
>> meet the gamma target [measured about 2.0, rather than 2.2 as I had
>> specified in the NCE GUI], and the chromaticity of the R=G=B ramp is
>> also still a little bit off neutral too.
>
> I've used the i1 that came with my XL20 on a laptop running XP
> with NCE profiling the screen of the laptop (and not the XL20).
> It did not be behave as your described, and did ramp.
Interesting. If the attached monitor was not an XL20 (e.g. if I switch
the graphics card driver to the laptop display), then IIRC NCE did not
offer me the opportunity to measure anything (-> button grayed out). Do
you possibly have a better version of NCE than I have (V.2.0.00)?
Regards,
Gerhard
Other related posts:
