Re: 1 billion colors
Re: 1 billion colors
- Subject: Re: 1 billion colors
- From: Steve Upton via colorsync-users <email@hidden>
- Date: Tue, 7 Jan 2020 12:58:51 -0800
> On Jan 6, 2020, at 1:36 PM, Roger Breton via colorsync-users
> <email@hidden> wrote:
>
> Well, Andrew, just to push the discussion further, I would *love* to hear
> what Steve Upton would have to say about “unique colors” since he’s the one
> that wrote the application: what numerical criteria does Steve use in
> ColorThink to distinguish among “unique colors”?
>
Gah!
I've been drawn into the angels-on-the-head-of-a-pin discussion again!
I agree with all of you... does that help?
I have to admit the "There's a color missing, prove me wrong" is pretty damn
funny. Good to get a chuckle from this stuff sometimes.
My 2 bits?
There's an interesting point here about the difference between addressable
colors and addressable unique colors.
For me (not necessarily using the correct terms) an addressable color in this
discussion would be any RGB value that results in a Yxy value that falls within
the chromaticity diagram and represents an actual, visible color. This includes
any precision level so imaginary 128bit-per-channel RGB spaces would be
included as well. There'd be a lot of wasted bits addressing imperceptible
color differences but they'd be real colors. This brings me to:
Addressable *unique* colors is the idea that perceptual spaces like Lab have a
kind of maximum resolution, where we could use a set of coordinates that is no
more precise than our ability to see the differences between colors. Each
unique color is effectively assigned a coordinate and we're good to go.
"But wait", you might say, "color perception is analogue and infinitely
variable" (nod to Mr Gnaegy, good to hear from you sir). "A hard-edged
coordinate system could never capture it!"
I agree that we're analogue beasties but it's not a problem. In our discussion
we're talking about trying to address unique colors. If we use such a
hard-edged coordinate system there's nothing saying it can't be slid around /
re-aligned with infinite precision, only that the differences between the
coordinates would need to remain the minimum perceptible difference between
colors - therefore it still addresses unique colors...
If I understand and slightly warp the intentions of our color forefathers
properly, CIELAB was intended to be just such a coordinate system, where 1 unit
of movement in any direction would be the human perceptual limit of color
change. If you added up the "volume" of such 1-unit cubes in a defined area,
such as a printer gamut, then you'd have a number representing the number of
unique colors available. That's exactly what I do in ColorThink.
Unfortunately CIELAB is flawed, or perhaps it's better to say that human color
perception doesn't adhere to such a simple model. Newer models have been
created such as CIECAM that help address some of these limitations. Suffice to
say that there's broad agreement that CIELAB and delta-E 76 are dangerous to
use naively, yet remain quite useful and delta-E 2000 helps bring color
differencing numbers more in line with human perception.
Though I recognized that the concept of a total gamut volume is disputable and
somewhat flawed from the start, I thought that it probably still had value and
chose to include it in ColorThink Pro. At the very least I thought it would
start some interesting discussions! Overall, I think it has been useful,
especially in a comparative sense.
Are there better ways of doing it? Undoubtedly. Is there agreement on which
ways are better? Not much that I can find yet, but work on the science
continues and we continue to learn as we go.
Those who are attending the Color20 Conference in San Diego next week will be
treated to a sneak peak of what's coming in ColorThink 4 later this year - like
new color spaces for graphing, advanced gamut comparison functions, and so
forth.
regards,
Steve
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