Re: Another quote from Roy Berns on metamerism-color inconstancy
Re: Another quote from Roy Berns on metamerism-color inconstancy
- Subject: Re: Another quote from Roy Berns on metamerism-color inconstancy
- From: Marco Ugolini <email@hidden>
- Date: Fri, 18 Jun 2010 17:55:15 -0700
- Thread-topic: Another quote from Roy Berns on metamerism-color inconstancy
In a message dated 6/18/10 12:20 AM, Steve Upton wrote:
> At 10:40 PM -0400 6/17/10, john castronovo wrote:
>> ----- Original Message ----- From: "Terence Wyse"
>>>
>>> Would this be color inconstancy or metameric failure?
>>
>> As I understand it, it would depend on what you're looking at and what's
>> changing. If you're comparing how two swatches fail to remain the same,
>> then that's a metamerism failure. If you're looking at how a single
>> swatch changes under different light, then that's inconstancy.
>
> OK... agreed, the definitions of the terms have been clearly documented,
> quoted and discussed.
>
> But let's just set them aside for a moment...
>
> Let's imagine I am carrying a printed gray patch around our office between
> solux, fluorescent, incandescent, daylight, etc and observing color shifts
> that are unexpected (not related to white point) and undesired. If I showed it
> to a customer they would likely be unhappy.
>
> Now, imagine that I perform the same spectral wanderings with an additional
> gray patch alongside for the ride. As I move from illuminant to illuminant do
> I see a different effect? Am I any happier? Would my customer be?
>
> Are the physics of the situation any different?
I'll let Berns say it:
"Each object forming a metameric pair has a different DEGREE OF COLOR
INCONSTANCY. [author's emphasis -- MU]"
That's a FACT. Opinions should account for facts, not ignore them because we
find them inconvenient or otherwise bothersome.
> Are the physiological and psychological effects different? Perhaps it could be
> argued that they differ, especially since there's a visual reference added to
> the mix.
I think that this introduces needless confusion. No one is arguing the
physics. No one is saying that green men from the 15th dimension will start
appearing after one stares at the sample for a given amount of time, or that
the observer will be transported to Alpha Centauri via a wormhole.
The physics are NOT in question. I never challenged the physics of the
viewing environment, nor does Berns. So, the question "are the physics any
different" represents what in logic is called a "straw man", a non-existent
assertion attributed to the other person which is then used to counter their
positions (usually by belittling them as self-evidently foolish based on the
misattributed invented claim).
> Ultimately though, it seems to me that we are looking at the same problem,
> caused by the same physical properties of the paper, inks, illuminants and
> receptors. The problem, in both cases, will need to be addressed in the same
> manner with the same techniques. In my opinion, the addition of a reference
> gray only serves to illustrate the problem more effectively, it doesn't change
> the root cause(s)
Again, "straw-man alert". I didn't ask for the addition of any gray
reference specimens. I only and exclusively advanced a point of proper
terminology. I wasn't reinventing the wheel and proposing a whole new
scientific approach (!), which I'm neither willing nor qualified to do.
> Are there situations in which the differences between constancy and metamerism
> DO make a significant difference? Probably.
What "differences between constancy and metamerism"? VISIBLE differences?
There are none. There are no "differences" to speak of, because both
phenomena (inconstancy and metamerism) are elements of the same general
process of viewing and visual appraisal.
I indicated several times that the concepts are both distinct AND related.
Berns says likewise in the quotes I offered, not in those exact words, but
unmistakably so (as in: "Each object forming a metameric pair has a
different DEGREE OF COLOR INCONSTANCY.").
> Do they apply to the graphic arts world?
Of course. Part of identifying and tackling a problem or practical challenge
is to define it by using the terms appropriate to it. Start "fuzzy", and one
may end up grappling with the wrong problem.
I don't ask that we "evangelize" designers or photographers on the value of
proper terminology. They don't care, and neither should they. It's WE, the
production and technology experts, who should care to stay aware, sharp and
alert, and not choose to cut corners, intellectually or otherwise.
> I personally doubt it, and that's why I choose to wade into the
> discussion.
>
> I'm not choosing to ignore a problem or gloss over an important issue. I just
> honestly believe that these arguments are the color management equivalent of
> how many angels can dance on the head of a pin.
Not in the least. Theological arguments are predicated on the absence of
evidence. The distinction between color inconstancy in a single sample on
the one hand, and a match between the elements of a metameric pair on the
other, is verifiable in reality, and repeatable, which is the hallmark of
science (as opposed to the unverifiable nature of theological diatribes).
> What we should be spending our efforts on is the outrageous elimination of any
> explicit non-color-managed pathway from Photoshop to an inkjet that doesn't
> involve the choosing of ICC profiles in two places and the crossing of
> fingers.
Studying proper terminology doesn't mean that we should stop taking care of
other issues that we may encounter while dealing with any technology or
procedure. It's not an "either/or". We can (and should) do both. Again, a
bit of a "straw man" here too, since I never advocated that we hold
everything else until everyone understands and uses proper terminology!
> "No really", we say to our customers, "to turn color management off, we need
> to turn it on."
>
> *that's* insanity.
And beside the point in this thread, Steve. Sorry, but it is.
Marco Ugolini
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