Re: [TheWildBunch] Re: Monitor profile verification [was: Eye One Pro for monitor calibration? [was: Re: NEC 2690 SpectraView]]
Re: [TheWildBunch] Re: Monitor profile verification [was: Eye One Pro for monitor calibration? [was: Re: NEC 2690 SpectraView]]
- Subject: Re: [TheWildBunch] Re: Monitor profile verification [was: Eye One Pro for monitor calibration? [was: Re: NEC 2690 SpectraView]]
- From: Andrew Rodney <email@hidden>
- Date: Sun, 02 Dec 2007 08:54:04 -0700
- Thread-topic: [TheWildBunch] Re: Monitor profile verification [was: Eye One Pro for monitor calibration? [was: Re: NEC 2690 SpectraView]]
On 12/2/07 2:05 AM, "Marco Ugolini" wrote:
> 1) Internal consistency: is the profile producing values close to the ones
> expected according to the measurement device used to create it?
Even if the instrument and software are way off the mark? Where's the value?
> 2) Absolute accuracy: how closely do the colorimetric values predicted by
> the profile match the colorimetric values actually measured by a
> *reference-grade* instrument?
Here we have far more value. We are comparing the results of a process based
on a known reference.
> Point 1 is within the reach of the "common mortal" type of user.
Which doesn't necessarily provide it any usefulness in and of itself.
> Point 2 is
> for the lucky ones (like Roger) who have access to a $25K+ reference
> instrument.
Point 2 does provide some usefulness. That its difficult for lots of users
is immaterial in what the results provide.
> To be practical about it, a color cast will be detectable even by way of
> visual inspection. If the device is *clearly inaccurate*, the discerning
> user will detect it.
As we see here?
http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
That attitude bodes well for the use of Adobe Gamma too.
> If the inaccuracies are minor and hardly detectable
> visually, then I wonder how important they are, ultimately.
They are important only if you're sure, over time that they are hardly
detectable. But combined over time, IF you could view them, they would
probably be detectable. You're looking, visually at a device displaying a
set of numbers in its current behavior. You can't compare how those numbers
may appear, based on TODAY's calibration in a month or a year. That may be a
problem. Ideally the same RGB and CMYK numbers produce the same color
appearance (and measurable color output) every time.
> In my opinion, an expert user learns fairly quickly whether or not one's
> measurement devices are trustworthy or not.
If that's true, all the validation processes you're talking about are
unnecessary, you'll know everything is correct by looking at the current
state of the display calibration.
> So, it seems clear to me that the verification process is merely an
> *internal consistency check* (how close are the measured numbers to the
> expected ones?). It's *not* an absolute accuracy check.
Again, if that's true, and what you're also saying is what you believe (" If
the device is *clearly inaccurate*, the discerning user will detect it.")
what's the point of all this?
Andrew Rodney
http://www.digitaldog.net/
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