Re: EyeOne Accuracy for FOGRA Proof Verification
Re: EyeOne Accuracy for FOGRA Proof Verification
- Subject: Re: EyeOne Accuracy for FOGRA Proof Verification
- From: Joseph Yates <email@hidden>
- Date: Mon, 11 Jun 2007 14:30:39 -1000
- Thread-topic: EyeOne Accuracy for FOGRA Proof Verification
> In a message dated 6/10/07 5:52 AM, Roger Breton wrote:
>
>>> Short term repeatability
>>
>> 0.1E* 94 (d50, 2°), mean value of 10 measurements
>> every 3 seconds on white
>
on 6/10/07 8:05 AM, Marco Ugolini at email@hidden wrote:>
> It's also true (and I think not repeated often enough) that if you make
> repeated measurements *without moving the EyeOne spectrophotometer*, the
> measurements are usually very close to one another, probably within the
> specs declared by the manufacturer.
>
> But as soon as you move the EyeOne, even a smidgen over the *very same*
> patch, and take another measurement, the new value may differ significantly
> from the previous one. I'm not sure why that is, since it's the same patch,
> but I suspect that it has something to do with the way the color is laid
> down ever so imperfectly and the substrate itself is not perfectly
> homogenous, and so on, so that even a slight move changes the color somewhat
> perceptibly (by the EyeOne, at least).
>
> So, when checking repeatability, do *not* move the device between
> measurements, and see what you get that way.
Which most likely explain why I am getting different readings from the ORIS
Certified Proof software - since measurement of the Media Wedge patches
always takes a reading from a different spot on the patches for each strip
reading. For example I've gotten deviations of between 4.44 - 4.87 on the
Max Primary patch
> the new value may differ significantly
> from the previous one.
I'm now seeing this - so how does one account for this in 'ISO Proof
Verification' workflows - where you are "certifying" that this particular
proof meets certain FOGRA tolerances - when in fact subsequent readings of
the same proof with the same instrument may "differ significantly"?
(Not to say anything about other instruments)
Or is a deviation of .4 to .5 not that significant for ISO proof
verification?
Joseph Yates | Pacifica Island Art | Maui, Hawaii
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