I guess you're right. In particular a tetrachromat human female will
perceive a different world from a run of the mill trichromat male ...
Edmund
On Tuesday, February 1, 2022, Iliah Borg <iliah.i.borg@xxxxxxxxx> wrote:
All of the possible perceivable colors
By definition, in colour science / technology colours are only what we
perceive. Colour here is not a phenomenon of physics, mathematics, or
anything else but perception.
Different combinations of wavelengths / intensities can be perceived as
the same colour.
On 2/1/22 11:20, Tucker Downs wrote:
All of the possible perceivable colors are organized in a quantitative--
and uniform way by their relationships with other colors... I think.
Actually, it is a good question but no matter what the answer is it's
certainly not easy or known today.
Mathematically, for example, our best models for chroma / achromatic
perception are unbounded. And lightness perception or brightness only has a
lower bound of zero.
But I think more theoretically you could say that the sensory perceptions
are bounded. You can only give so much signal to each of the cones and
there's a limit to the spatial organization of those stimuli on the retina.
And so there is some limit to the possible inputs and therefore some limit
to the possible outputs. For example you can't signal the cones in such a
way that you will get both a yellowish hue and a bluish hue at the same
time (they are opponent pairs developed in retinal neurophysiology)
Then there are considerations to be made in the brain. The
neurophysiology of the brain is not entirely well known (or hardly known at
all) but there is a hypothesis that in the early stages of vision there is
a collection of neurons, maybe 7-8 for each visual area) that encode hue.
I've heard this called hue map theory. Where you have a neron for red,
orange, yellow, green, cyan... etc hues. Maybe there is some way
(artificially?) to trigger these neurons in a way that is not possible via
the opponent mechanism. Then perhaps there would be a new perception of
color, or a more intense larger value of some color in a quantitative
system. Does that count as being a part of the perceptual gamut? Even if
hue map is destined to be disproven, it's easy to imagine that there are
other perceptual mechanisms that could be exploited the same way.
Getting back to Mizen's original question, if you just mean what is the
range of possible stimulus that this display can make vs. the limit of
stimulus for the retina, you can refer to the XYZ space or chromaticity
diagrams as the above have mentioned. You could even transform those XYZ
values into CIECAM values with several assumptions. but this road is
fraught with tempting errors and assumptions, and isn't built on visually
verified color scales. CIECAM and other perceptual color spaces are
optimized for color comparisons that are "normal" not at the limit of
visual perception.
If you do actually mean to be properly considering the limits of visual
perception there are a number of university research groups throughout the
world that would be interested in discussing it.
Good luck! :)
- Tucker
On Tue, Feb 1, 2022 at 10:55 AM Iliah Borg <iliah.i.borg@xxxxxxxxx
<mailto:iliah.i.borg@xxxxxxxxx>> wrote:
IMO a good start is to define the terms. How do you define "human
visual
perceptual gamut"?
On 1/31/22 18:22, Mizen Mark (MMizen) wrote:
> I am looking for a text file or color profile that reflects the
human
> visual perceptual gamut so that I can compare the human visual
gamut to
> my device profile. I believe this information exists, but I was not
> successful in locating it in a form that I could use for the
comparison.
> Thanks.
>
> Mark
>
> Mark Mizen, Ph.D.*
> *Principal Advanced Development Engineer, Secure Issuance
> Office: 952 946 8463 | Mobile: 952 288 6488
> mmizen@xxxxxxxxxxxxx <mailto:mmizen@xxxxxxxxxxxxx>
<mailto:mmizen@xxxxxxxxxxxxx ;<mailto:mmizen@xxxxxxxxxxxxx>>
>
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-- Best regards,
Iliah Borg
LibRaw, LLC
www.libraw.org <http://www.libraw.org>
www.rawdigger.com <http://www.rawdigger.com>
www.fastrawviewer.com <http://www.fastrawviewer.com>
Best regards,
Iliah Borg
LibRaw, LLC
www.libraw.org
www.rawdigger.com
www.fastrawviewer.com
