Re: Monitor calibration software/hardware
Re: Monitor calibration software/hardware
- Subject: Re: Monitor calibration software/hardware
- From: Marco Ugolini <email@hidden>
- Date: Sat, 22 Sep 2007 20:16:03 -0700
- Thread-topic: Monitor calibration software/hardware
Hi Tom.
I appreciate your taking the time to reply.
In places, though, your message appears obscure or unclear to me, so I will
ask you to explain a few terms and statements.
In a message dated 9/22/07 2:45 PM, Tom Lianza wrote:
> Using an independent reference, on certain displays, DTP94 did well
> and on others, there where issues. The same was true with the i1Display2.
> There is a definate population difference between the two products
> because they are calibrated to two different standards.
What is the meaning of "population difference" in this context? Which
"population"?
> We found that the difference between the two primary standard measurement
> insturments, when looking at certain LCD's, could yield deltas as high as
> .006.xy. Keep in mind that number is on the order of the specification for the
> i1Display2. The stated accuracy of the 15,000 dollar PR650 is on the order of
> .006xy on any color measurement of a CRT source.
The specified tolerances for the EyeOne Display 2 and of the Photo Research
PR-650 SpectraScan Colorimeter, when used with a CRT, are the same? Is that
so? That sounds hard to believe.
> I liked the DTP94, but it was slow, it had quantization issues in the deep
> dark and in very saturated colors. This gave the appearance of a highly
> repeatable instrument except when subjected to critical testing by engineers.
So, are you saying that, all things considered, and in your judgment, the
EyeOne Display 2 is actually a finer instrument than the DTP94/Optix XR?
Mind you, I'm not challenging that: I'm only asking for your expert and
honest opinion.
> Some comments about specs:
> If you look at the specifications for a low cost colorimeter FROM ANY VENDOR,
> you will find that the stated variablity can produce visible difference
> between displays and calibrators. This means that if I take one
> calibrator/display pair and compare that to another calibrator/pair you can
> expect to see a difference even if the products are in spec. If you took
> two,$15000, pr650 spectro radiometers, on two unique displays, you could end
> up with an 8 to 12 deltaE difference between displays and still be within the
> stated spec of the reference instruments. Just because you see a difference,
> it doesn't mean that the product is out of spec or has "gone bad".
That is still not clear to me, so let me rephrase it. Are you saying that
two reference-grade spectroradiometers, each of which is used on a unique
display to implement a similarly structured calibration/profile procedure,
will produce visual results on each of the two display that differ as much
as 8 to 12 DeltaE from one another, though the reference-grade colorimeters
themselves operate within specs?
Why would that be, exactly? I don't understand. You're saying that "the
stated variability can produce visible difference between displays and
calibrators", but is that intended to mean that the stated tolerance of the
spectroradiometers themselves will possibly cause those very visible
differences?
> End user displays, particularly on laptops are getting worse,
> not better,
I noticed... <g>
As an example, I also noticed an appreciable *decrease* in the quality of
the latest generations of the Apple Cinema Display family of LCD monitors.
My guess is that it's but one of the many consequences of the worldwide race
to the bottom in manufacturing and labor costs following market
globalization.
> and as displays get brighter and are used in higher ambient conditions,
> we find the various aspects of appearance predominate the color puzzle.
Meaning...?
Thank you for your time and patience.
Marco Ugolini
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