Wire, I'm not really after one "best" visualization. MacAdam ellipses are daunting to me, I won't go there unless I have to. I realize no color space will ever have perfect qualities but that's not what I'm after... My point, in raising the question with Steve yesterday, was what kind of numerical abstraction can be applied to distinguish between "unique" colors -- sorry to sound like a broken record in the context of color management? I confess, initially, I had this 16.7 million RGB "color combinations" question in mind. But, like many here, I am aware of research that concluded that men and women with "normal color vision" can only discriminate 10 million different colors (or something like that?) which is referred as the "Gamut of real colors", I think, see Dr Michael Pointer -- a nice guy, btw 😉 I never read the papers about this concept (I have no idea how that number was ever arrived at or very vaguely) but I took it "on faith" that this estimate made intuitive sense to me. There are only 24 hours in a day. / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca@lists.apple.com> On Behalf Of Wire ~ via colorsync-users Sent: Wednesday, January 8, 2020 8:39 AM To: 'colorsync-users?lists.apple.com' List <colorsync-users@lists.apple.com> Subject: Re: 1 billion colors On Tue, Jan 7, 2020 at 14:21 Steve Upton via colorsync-users < colorsync-users@lists.apple.com> wrote:
On Jan 7, 2020, at 1:36 PM, Roger Breton via colorsync-users < colorsync-users@lists.apple.com> 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. _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx@videotron.ca
On Wed, Jan 8, 2020 at 06:07 Roger Breton via colorsync-users < colorsync-users@lists.apple.com> wrote:
Wire,
I'm not really after one "best" visualization. MacAdam ellipses are daunting to me, I won't go there unless I have to. I realize no color space will ever have perfect qualities but that's not what I'm after... My point, in raising the question with Steve yesterday, was what kind of numerical abstraction can be applied to distinguish between "unique" colors -- sorry to sound like a broken record in the context of color management? [...]
The 16 million colors thing is overloaded. In the context of your queries, all it is about is a data format for encoding of stimuli (the light coming out of your display) that ensures sufficient variety to produce smooth gradations. Because we are talking about the display's data interface, and because you can count the stimuli produced for a pixel input value 1-to-1, and because as stimuli — using this word advisedly — the effects are totally within a visible range, the count of a pixel value at the display input is considered to be a count of colors the display can produce. That's it. No further parsing or interpretation is needed. You don't want all the inputs to be perceptually distinct, because you want gradients to be smooth, but for cost you don't want way more than you need for sufficient response. In the early days of graphics, pixels and colors were scarce and expensive and color was coarse. Now its possible to over-provision values, and new ranges of brighter higher gamut output are available. Color is rich and smooth. Given the traditional limits of the device data formats, there are other ways of getting the most out of limited pixel color values. For example, you can vary the tonal response curve, aka gamma, and you can use pixels in groups: dither and subpixel rendering are common tactics to get perceptually smoother overall response from a system at limits of visible quantization artifacts confess, initially, I had this 16.7 million RGB "color combinations"
question in mind. But, like many here, I am aware of research that concluded that men and women with "normal color vision" can only discriminate 10 million different colors (or something like that?) which is referred as the "Gamut of real colors", I think, see Dr Michael Pointer -- a nice guy, btw 😉 I never read the papers about this concept (I have no idea how that number was ever arrived at or very vaguely) but I took it "on faith" that this estimate made intuitive sense to me.
There are only 24 hours in a day.
/ Roger
I find the idea of countable colors in sense of max perceivable to be at edge of a red herring. Ask why you want an answer to this question... and if you don't know exactly why you might abandon it for now and see where it pops up again. Ya I'm interested in idea of Pointer's gamut too but I don't think it involves counting.
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