Re: Viewer perception of neutral gray
Re: Viewer perception of neutral gray
- Subject: Re: Viewer perception of neutral gray
- From: Roger Breton <email@hidden>
- Date: Tue, 04 Sep 2007 19:06:30 -0400
Mark,
> 1. People have 3 types of color receptors in their eyes, often known as
> alpha, beta and gamma.
Robert Hunt would use gamma (red), beta (green) and rho (blue), but we get
the idea.
> 2. Each type of receptor very roughly corresponds to red, green and blue.
Right.
> 3. However, the spectral curve shape of each type of receptor is very broad
> and overlaps significantly with the next type of receptor.
Especially between the gamma cones and the beta cones. Much less in the rho
cones.
> 4. There is no proof that all people have equal spectral response to broad
> spectrums, or anything else for that matter.
"On average" is the key word. On average we all do. But, true, there are
wild variations in the proportions of the three types of cones and yet THEY
STILL SEE THE SAME COLOR! Meaning see the same pairs of color as a match.
The brain is doing something behind the scene but we don't know what it is.
> 5. Since we know that "color blind" people exist, it is very unlikely that
> most people have equivalent spectral response.
True. Which leads in the idea of "observer metamerism".
> 6. What does this do to "metamerism" or "color inconstancy"?
To me, "inconstancy" is an invariant. It's just a way to make a prediction
about the appearance of an object color as it will be viewed from one set of
conditions to another. Granted it does not say anything about who's doing
the observation. But all we can say is that, on average, the change of
appearance will be seen by most people.
> I suspect it alters it considerably.
Yes, I agree. Throw in "observer metamerism" on top of whathever "color
inconstancy" a given specimen exhibit and we're into the realm of a color
circus.
> Mark Rice
Roger Breton
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