Re: 1 billion colors
Re: 1 billion colors
- Subject: Re: 1 billion colors
- From: Wire ~ via colorsync-users <email@hidden>
- Date: Wed, 8 Jan 2020 05:38:51 -0800
On Tue, Jan 7, 2020 at 14:21 Steve Upton via colorsync-users <
email@hidden> wrote:
>
>
> > On Jan 7, 2020, at 1:36 PM, Roger Breton via colorsync-users <
> email@hidden> wrote:
> >
> > So, Steve, anything that is outside of that "1 Lab" unique cube is
> considered a "different color", in ColorThink? Is that your criteria?
>
> effectively, yes.
>
> Though if you "do the math", it becomes clear that 1 Lab cubes don't pack
> properly so that the centers of each cube are 1 dE apart from all the other
> centers, *and* that you can't really do that because sphere's don't pack
> efficiently, etc, etc, etc
>
> Steve
>
Roger, it seems you are thinking about something like packing of MacAdam
ellipses...
https://en.m.wikipedia.org/wiki/MacAdam_ellipse
The MacAdams ellipse describes relative capacity to distinguish color
across regions of the locus.
Normal individual observers — normal meaning those who you would not define
as color-blind — will have varying abilities to discriminate depending on
the color.
(Is it fair to use the term color in this way? If color is a pure qualia
can you have color blindness? How can one be blind to that which for him
does not exist? ;)
The idea is you pick a coordinate and ask how well an individual, as
compared to the population, is able to discriminate difference surrounding
this coordinate? And how sensitive is the population to differences across
the gamut (word police: "we have you surrounded").
The MacAdam idea leads to a heap or camel or Zeno's paradox: Pick a point
and draw a MacAdam ellipse. Within the ellipse, color is considered
indistinguishable. Between the neighboring ellipses, color is
distinguishable. Pick a point half-way between neighboring ellipses and draw
another MacAdam ellipse. Where did the color go?!
This may leads me to consider I want an encoding system with a resolution
much finer than one standard color difference. Say if I had a system of
millions of "colors" nee qualia (oh, wait, strike that, reverse it... Er no
wait... waaaahhhg!) and I want a stimulus system that driven by a
numerical non-uniformly
perceptually distributed integer RGB values to avoid visible quantization
artifacts, I may find I want the data format to encode a couple orders of
magnitude more stimulus than qualia to ensure I cover the corner cases.
Therefore "billions of colors."
QED
Seeing this MacAdam idea really affected my visualization of the
distortions inherent to the XY plot. And cemented my view that Adobe RGB
was singled-minded in desire to cover press, with newer DCI being a much
more balanced extension of sRGB.
As somewhat related aside, DisplayCal has gamut projections in a mode
called DIN99, which looks to me like it might be intended to be a very
perceptually weighted plot. There's not much about it returned by web
search... I admit I haven't asked at the obvious place, over at the DCal
forum.
I'll post the Dell gamut vs standard gamuts as DIN99 so others can see.
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