Re: Heads up Samsung XL20, 24 & 30
Re: Heads up Samsung XL20, 24 & 30
- Subject: Re: Heads up Samsung XL20, 24 & 30
- From: Roger Breton <email@hidden>
- Date: Wed, 05 Dec 2007 21:11:45 -0500
>> The criteria for the evaluation of this product shall focus on its
>> abilities for soft proofing for the graphics industry.
Maybe throw in reference images like the ISO-SCID CMYK images or the
ISO-sRGB images (even if they are not wide gamut) or the bvdm Roman16 eciRGB
images. Those are excellent choices. And you need them in print form as
well.
Softproofing is no doubt important but let's not neglect the technical
qualities of the monitor. Like, what is the uniformity in Y and chromaticity
across the surface? Does it meet ISO-12646 requirements for instance?
You will have to publish the spectral radiance for each R,G,B color as well
as white, C,M and Y. We want to study the shape of the LED spectra.
>> - Grey balance? L* calibration, Gamma?
Calibrated gray balance. How neutral do the grays appear once calibrated? Do
they look most neutral at D50, D65? I guess that might depend on the
instrument used to carry the calibration and profiling to some extent but
perhaps we should use some kind of grey reference material viewed under a
JUST or GTI light booth. Maybe some NCS sheets or Munsell N8 or N7 8.5 x 11
sheets.
I'd like to see references to some real world popular physical references
such as the Macbeth ColorChecker Chart or the DC or the SG. And I'd like to
have observer ratings to those chart's appearance.
> I'm very comfortable with L* calibrated displays for softproofing.
> CIECAM02 is also an alternative (namely for other viewing conditions).
It would be interesting to see how the monitor fares relative to some target
gamma behavior. Maybe L* will be best? Maybe a fixed gamma like 2.2?
>> - What profiles? LUT? Matrix?
> There is no need for sophisticated gamut mapping or different rendering
> intents in a wide gamut display profile. As long as the device can be
> characterized accurately by a matrix profile, it is absolutely adequate.
While you're at it, why not test the predicted performance of the display
relative to some profile types? Is there an advantage for using a LUT
profile over a simple matrix/TRC profile? Which type provide the best
colorimetric performance on this particular display?
Along these lines, what is the channel independence? Does the chromaticity
remain constant when raising each channels digital code values from 0 to
255?
>> - What testing software? UDACT (UGRA.ch), ColorEyes
>> (Integrated-color.com, ColorThink from Chromix.com, ColorPursuit from
>> Alwancolor.com, Xrite Profilemaker Measure tool www.xrite.com)?
> UDACT is a approved, simple quality control tool for end user. Tools
> like ColorPursuit are useful to acquire more detailed analyses.
Of course, first and foremost, everyone will want to know how the monitor
fares using its bundled software package. Whichever software used to test
the monitor, whether UDACT or BabelColor's PatchTool, for instance, will
*have* to have all assumptions laid out extensively. In the case of UDACT,
for example, we all know that the software does not enforce strict
conformance to 12646 as far as white point calibration is concerned. So, it
will not be enough to say something like "meets the UDACT's test" because
the testing can be configured in many ways and everyone of them will yield
valid results!
>> - What standards? ISOCoatedv2 (Fogra 39L), Gracol, SWOP, JAPAN COLOR?
>>
> FOGRA39 or GRACoL Coated 1 (the gamut differences are negligible): they
> cover nearly every other standardized printing process.
Given the wide gamut nature of the display, FOGRA39L and GRACoL_C1 are de
facto requirements, no? But other datasets should be attempted as well such
as SWOP2006_Cx.
>> - Uniformity? Acceptable variance and testing methods?
> very important, but hard to measure/compare.
Read the ISO-12646 requirements. Look at BabelColor's CT&A for ISO-3664
testing requirements for monitors. Could even use that as a test bench with
supported instruments like the EyeOnePro and the Spyder.
> The same applies to angular failures (I wish there were something
> like a standardized procedure to create a "map" of Delta E max as a
> function of the viewing angle)
That's very important. I'd be really disappointed if the angular performance
was be no better than the Samsung 245bw.
Roger Breton
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