Re: Accuray of EyeOnePro
Re: Accuray of EyeOnePro
- Subject: Re: Accuray of EyeOnePro
- From: Roger Breton <email@hidden>
- Date: Tue, 30 Oct 2007 07:04:52 -0400
Kag dielo Alexei!
Thank's for your kind reply.
> You missed the folloving statement:
>
> -----------------------------------
> Inter-instrument agreement:
> Average DE*94 0.4, max. DE*94 1.0
> (Deviation from X-Rite manufacturing
> standard at 23°C for single
> measurement mode on 12 BCRA tiles (D50,2°)
> -----------------------------------
The problem with "inter-instrument agreement" is that it only says how close
each i1pros coming out of the assembly lines measures relative to the
*master* instrument. Unfortunately, that is not a statement of accuracy. For
example, all i1pros could be off by a huge margin and still be within the
inter-instrument specs, you see. That does not help. That says something
about the quality of the instrument but nothing about its accuracy.
> IMHO it almost the same as accuracy. I told "almost" because it's not
> absolute accuracy but relative to Gretag's internal standard.
Accuracy is relative to some known standard. For example, in emissive mode,
it is standard practice in the color instruments industry to use an absolute
radiometrically calibrated light source such as tungsten lamp and use that
as a bench test. What they do is first measure the lamp with the best
instrument they can get (NIST, PTB, NRC) to obtain the "true" measurement.
Then, they measure the same lamp with the i1pro. They note the difference,
typically in xy chromaticity or in Y luminance and report that in their
specs. See, for example, what Minolta has to say about the specs of their
CA-210 here:
http://www.konicaminolta.com/instruments/products/display/color-analyzer/ca2
10/specifications.html
Read the section on Accuracy. They state accuracy for various luminance
ranges :
- 0.10 to 4.99cd/m2: ±0.008 for white
- 5.00 to 39.99cd/m2: ±0.005 for white
- 40.00 to 1000 cd/m2: ±0.003 for white
- 160 cd/m2: ±0.002 for white; ± 0.004 for monochrome
So, for example, @160 candelas/meter2, they state the CA-210 has an accuracy
of ±0.002 for white and ± 0.004 for monochrome in xy.
That's the kind of statement I'm after from X-Rite on the i1pro. But, I
suspect for marketing reasons, we'll never see those specs published
anywhere -- it is not even in the SDK!
Roger Breton
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