January 2020 - colorsync-users

RE: Humans (and cameras and scanners) do not have a color gamut (?)
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

Henry, By "design", they can't have bounds, right? So, yeah, they all have their secret sauces to break the world of luminances down to RGB numbers. They don't have gamuts -- believe what you want. / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Henry Davis via colorsync-users Sent: Tuesday, January 7, 2020 5:28 PM To: colorsync-users(a)lists.apple.com Subject: Re: Humans (and cameras and scanners) do not have a color gamut (?) Thanks for helping but I’m struggling with how a camera can have no bounds. If different cameras have different responses it seems to me that one of them or both must be limited. Either that or they just have different ways of assigning numbers to the same bucket of input values. Henry Davis > On Jan 7, 2020, at 5:18 PM, Roger Breton via colorsync-users <colorsync-users(a)lists.apple.com> wrote: > > Henry, > > I agree, the visible spectrum has a (physical) "limit" but not the camera? No two cameras are likely to have the same response to the spectrum locus. The limit, in this case, is in the "object" being captured -- not in the camera itself. > > Do you see the difference? _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx(a)videotron.ca

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RE: Humans (and cameras and scanners) do not have a color gamut (?)
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

Henry, I agree, the visible spectrum has a (physical) "limit" but not the camera? No two cameras are likely to have the same response to the spectrum locus. The limit, in this case, is in the "object" being captured -- not in the camera itself. Do you see the difference? / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Henry Davis via colorsync-users Sent: Tuesday, January 7, 2020 5:17 PM To: colorsync-users(a)lists.apple.com Subject: Re: Humans (and cameras and scanners) do not have a color gamut (?) Thanks Roger. What I don’t understand is the idea that the visible spectrum as I understand it has some sort of gamut - it has defined ends. That seems like a gamut to me. Henry Davis > On Jan 7, 2020, at 4:55 PM, Roger Breton via colorsync-users <colorsync-users(a)lists.apple.com> wrote: > > Henry, > > I'm not a digital camera designer but what don't you understand about the fact that a camera is a sophisticated "light detection system"? It's pretty much a color measuring instrument (others could correct me) but an i1pro does not have a "gamut" per se or a filter-based colorimeter, they take light in and spit out numbers in response -- same with digital cameras, they take light in and spit out sets of RGB numbers. Surely there's a lot of math going on inside the CPU of a Nikon or a Canon or a SONY camera, like estimation of scene illuminant by which tonal responses are likely adjusted. There may very well be some kind of "model" of various 'natural scenes' because, just like during the creation of output profiles, it helps to have some kind of "assumptions" as to what ranges of colors or luminances are to be expected. But is that a"gamut" per se? A gamut is a physical construct, it comes from something measurable that have "limits". > > I hope that helps... > > / Roger _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx(a)videotron.ca

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RE: NEC PA271Q "Native" chromaticities
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

David, It comes back to my "idea" of "threshold"; what's the 'criteria' that makes two colors appear "different" to a 'normal observer'? It has to be 'measurably' different otherwise, we're going to argue until the cows come home. / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of David Scharf via colorsync-users Sent: Monday, January 6, 2020 7:32 PM To: Andrew Rodney <andrew(a)digitaldog.net>; david(a)scharfphoto.com; Florian Höch via colorsync-users <colorsync-users(a)lists.apple.com> Cc: David Scharf <electronman(a)roadrunner.com> Subject: Re: NEC PA271Q "Native" chromaticities Hi Andrew, My point was that when there are colors separated by an extremely small increment, they may be indistinguishable from each other and we may may perceive them to be the same color--so not invisible but visible--just not perceptually different. Seems like we are making two different valid arguments. DAVID SCHARF PHOTOGRAPHY *DAVID SCHARF PHOTOGRAPHY* Scanning Electron Microscopy http://www.electronmicro.com This email sent to graxx(a)videotron.ca

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RE: 1 billion colors
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

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”? In the meantime, I’m willing to buy 208,486 😊 / Roger From: Andrew Rodney <andrew(a)digitaldog.net> Sent: Monday, January 6, 2020 4:31 PM To: <graxx(a)videotron.ca> <graxx(a)videotron.ca>; Andrew Rodney via colorsync-users <colorsync-users(a)lists.apple.com> Subject: Re: 1 billion colors Got a copy of ColorThink Pro? Take the TIFF, load it into that product, Extract all unique color values into a color list. What do you get? I get 208486. Then use Convert all colors to list, what do you get? I get 250000 You got a silly answer ("1 is missing") but there are tools to actually analyze such a document without the need to assume..... Andrew Rodney http://www.digitaldog.net/ On Jan 6, 2020, at 1:58 PM, Roger Breton via colorsync-users <colorsync-users(a)lists.apple.com <mailto:colorsync-users@lists.apple.com> > wrote: Is anyone able to discriminate between the 16.7 million colors in this 24-bit RGB image? https://1drv.ms/u/s!AkD78CVR1NBqko8JmNRgIB2qvxz-iA?e=7il8Xk Be honest. / Roger _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users(a)lists.apple.com <mailto:colorsync-users@lists.apple.com> ) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/andrew%40digitaldog… This email sent to andrew(a)digitaldog.net <mailto:andrew@digitaldog.net>

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RE: perceptual differences in Lab deltaE
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

Ilah, Glad you brought this up because that's exactly one my current "pet projects". My code is not finished yet but basically, I'm going to be sweeping the entire "1024" scale with my instrument, to determine, exactly, what is what. I'll be glad to report as soon as I'm done -- can't wait! / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Iliah Borg via colorsync-users Sent: Tuesday, January 7, 2020 3:18 PM To: Wire ~ <wire(a)lexiphanicism.com> Cc: 'colorsync-users?lists.apple.com' List <colorsync-users(a)lists.apple.com> Subject: Re: perceptual differences in Lab deltaE On Jan 7, 2020, at 2:31 PM, Wire ~ via colorsync-users wrote: > the gear industry brags about capability to produce a range of > stimuli. Wait a minute. 10-bit, 8-bit, 12-bit... A device has particular capabilities. Is there a demonstration, using a spectroradiometer, that a "10-bit" display is capable of producing 1024 stimuli in each channel - even before we account for viewing conditions / flare? -- Best regards, Iliah Borg LibRaw, LLC www.libraw.org www.rawdigger.com www.fastrawviewer.com _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/graxx%40videotron.ca This email sent to graxx(a)videotron.ca

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Re: 1 billion colors
by Henry Davis 07 Jan '20

07 Jan '20

What resolution is the sky? Somewhere along the line the effects of resolution must’ve been addressed and I missed it. Or, does resolution not figure in to it? Henry Davis ________________________________________ Message: 3 Date: Mon, 06 Jan 2020 15:07:42 -0800 From: John Gnaegy <gnaegy(a)apple.com <mailto:gnaegy@apple.com>> To: colorsync-users(a)lists.apple.com <mailto:colorsync-users@lists.apple.com> Subject: Re: 1 billion colors Message-ID: <44DD1EC2-099F-4B50-ACDB-CF9565FBF6DD(a)apple.com <mailto:44DD1EC2-099F-4B50-ACDB-CF9565FBF6DD@apple.com>> Content-Type: text/plain; charset=us-ascii So is there anywhere you can see a nice, smooth, imperceptibly changing gradient? Turns out yeah. The sky. Go out and look at how smoothly the sky transitions from one color overhead to a wildly different color at the horizon (I mean without clouds). It's pretty amazing. And it kind of makes me want to never look at a display again.

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RE: NEC PA271Q "Native" chromaticities
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

Hey David, You're absolutely right. Not everyone "sees" color exactly the same way but, as I was once told by Mark Fairchild, on "average", we see color the same "way". I agree with you that the viewing conditions determine to a large extent the way we see color, and you could make the case that it would affect the "average" user the same way, too (I hope this makes sense?). How the patches are presented to the viewer, too, influences the way the color appear -- no question. Such a fascinating subject... / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of David Scharf via colorsync-users Sent: Monday, January 6, 2020 11:19 PM To: colorsync-users(a)lists.apple.com Cc: David Scharf <electronman(a)roadrunner.com> Subject: Re: NEC PA271Q "Native" chromaticities Hey Roger, The threshold of differentiation is, I suspect, different for different people, taking into consideration the brain as "computer" or perceiver and the eye as camera or sensor. Environment will also be a big factor--or how the colors are presented: two patches close in color next to each other will be more easily distinguishable that those colors presented amongst other disparate colors. David -- DAVID SCHARF PHOTOGRAPHY

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perceptual differences in Lab deltaE
by simon＠richstitch.com 07 Jan '20

07 Jan '20

Hi Andrew, I did some tests a few years ago by printing charts patches to exhibit small deltaE variations. My conclusion at the time was that the limit of deltaE of ≤ 1 was fine for colours with values of a or b > ±10 but as the colour approached the neutral (L) axis in the range 40 ≤ L ≤ 70 smaller values of deltaE were clearly visible. Most of my test subjects could detect differences of about 0.3 when the patches were compared side-by-side, and (almost a neutral grey). My conclusion from this was not surprising - for all my test subjects the Lab space was not perfectly perceptually uniform, and detecting differences in deltaE was significantly easier for values of -3 ≤ (a or b) ≤ 3 when comparing patches side-by-side. Simon simon(a)richstitch.com

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RE: NEC PA271Q "Native" chromaticities
by graxx＠videotron.ca 07 Jan '20

07 Jan '20

> I mean that in Adobe RBB mode, it's not unreasonable to predict that Dell > hits 2 delta-E conformance across the population. IOW, yes consistency > across the face of one panel, and conformance of the population to the > standard color space. Here's a screen capture showing the difference between the Dell UP2516 and AdobeRGB: https://1drv.ms/u/s!AkD78CVR1NBqkoskUPmmGmwKuk7b4Q?e=ldqlgr It's not bad at all. I don't know if it amounts to 2 DeltaE? But it's possible. Does DispCal (Argyll) have any tools to test this hypothesis? We are indeed living in a "golden age" of technology. / Roger

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(no subject)
by Wire ~ 06 Jan '20

06 Jan '20

As a total aside, I've received two "confirmation is required to leave the colorsync-users mailing list" in the last 2 days. But I've not requested this. Maybe I'm somehow misusing the list mechanism? But in the off chance someone is being passive aggressive, I'm open to a private message about any complaint and I won't take it public. I'm trying to have fun, which for me is Socratic. and this is naturally contentious.. If I'm offending anyone, I'd appreciate the chance to hear it out and make amends. TIA /wire

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