January 2020 - colorsync-users

Re: Humans (and cameras and scanners) do not have a color gamut (?)
by Rich Wagner 19 Oct '20

19 Oct '20

I agree with Florian’s responses below regarding how we “know” what animals “see.” The parallel question is how we “know” what women with tetrachromatic vision “see.” There is a very good article from the BBC that describes this that might help. https://www.bbc.com/future/article/20140905-the-women-with-super-human-visi… Here’s a short excerpt from the excellent story: Proving that these people actually see the world differently has involved a two-decade journey, however. Although the relevant combination of genes does not seem to be especially rare – perhaps 12% of women might have four distinct cones – many of the people that Jordan tested just didn’t seem to show any differences in their perception. But by 2010, she had found a subject who perfectly acted the part of a tetrachromat. Jordan’s “acid test” involved coloured discs showing different mixtures of pigment, such as a green made of yellow and blue. The mixtures were too subtle for most people to notice: almost all people would see the same shade of olive green, but each combination should give out a subtly different spectrum of light that would be perceptible to someone with a fourth cone. Sure enough, Jordan’s subject was able to differentiate between the different mixtures each time <http://www.journalofvision.org/content/10/8/12.full>. “When you ask them to discriminate between the two mixtures, a tetrachromat can do it very quickly. They don’t hesitate,” says Jordan. Unfortunately, much of the research in color perception is highly complex and often difficult for the lay public to comprehend. Good science writers can translate that research into language the lay public can understand. Poor science writing leads to exaggerated claims and misinformation. That said, the title of this article is a bit over the top. I don’t think these women have “super human vision” any more than those who are colorblind have “sub human vision.” Both have visual perception that is significantly different from the average of our species. —Rich > OnMon, 13 Jan 2020 19:40:11 +0100, Florian Hoech <lists+colorsync-users(a)hoech.org <mailto:lists+colorsync-users@hoech.org>> wrote: > [snip] >> Not a single case can be made by anyone?s fisthand information about the post processing by the brains of these animals. Who can know what they see or apprehend? > > You can draw pretty useful conclusions (meaning they work well in > real-life, thus supporting the respective theories) from all the > scientific research that has been done. "Color" perception is not just > "nice to have". Trichromats (like humans) have an evolutionary edge over > (say) dichromats, e.g. when it comes to distinguish edible/nutritious > from inedible/less nutritious food like fruits etc. When you look at the > M and L cone responses of any trichromat, you can see that the responses > of the "sensors" (cones) largely overlap. Yet, we seem to perceive the > "end result", green and red, as very different colors (opposites even!). > >> Since humans communicate with each other about color we can build models and references and so on. But animals? Yet, experts are quick to supply examples of how things must appear to non-humans. > > I think you may be conflating the actual research with how it is > presented (usually not by the researchers themselves), broken down and > simplified in newspapers/magazines/articles, online and offline, meant > for consumption by the general public. > >> When we grant that all of these theories are onto something about the ways animals percieve color we account for their differences by describing them in terms of ?gamuts?. > > I like the term "dimensions". A Tetrachromat has an additional dimension > of "color". > >> Surprise: experts determine gamuts based on the sensor alone! They don?t even seem to be the slightest bit unhappy about it. > > ...where? And who? Dimensionality alone doesn't really tell us much > about gamuts. > > Florian. >

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RE: i1Pro3 review
by graxx＠videotron.ca 31 Jan '20

31 Jan '20

Good show, Scott. One silly question, if I may, since the i1Pro3 aperture is larger, and charts need to account for that fact, did X-Rite have to the increase the size of the iO Table? / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Scott Martin via colorsync-users Sent: Friday, January 31, 2020 10:54 AM To: 'colorsync-users?lists.apple.com' List <colorsync-users(a)lists.apple.com> Subject: i1Pro3 review I’ve been working with the i1Pro3 “standard aperture” for a few months now and just posted a short review, FYI: https://www.on-sight.com/xrite-i1pro3-standard-aperture-review/ <http://www.on-sight.com/xrite-i1pro3-standard-aperture-review/> Short story: it’s great! Just like you’d expect, with only one surprise: strip reading is really much more forgiving. Cheers. Scott Martin www.on-sight.com Precise color science for printmaking professionals

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i1Pro3 review
by Scott Martin 31 Jan '20

31 Jan '20

I’ve been working with the i1Pro3 “standard aperture” for a few months now and just posted a short review, FYI: https://www.on-sight.com/xrite-i1pro3-standard-aperture-review/ <http://www.on-sight.com/xrite-i1pro3-standard-aperture-review/> Short story: it’s great! Just like you’d expect, with only one surprise: strip reading is really much more forgiving. Cheers. Scott Martin www.on-sight.com Precise color science for printmaking professionals

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is this thing on?
by John Gnaegy 30 Jan '20

30 Jan '20

Check one, check two... wondering if the list server is somehow stuck.

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RE: Observation observations.
by graxx＠videotron.ca 16 Jan '20

16 Jan '20

Actually I call that a "creative" methodology -- what a good idea, an "Adjustment layer", Photoshop's application in ophthalmology! What about the zillion of images you color-corrected on your computer before the surgery; did they still appear "correct", with your Adjustment layer? How long, would you say, you had to use and adjustment layer in your work, Craig? I remember one photographer I helped with his Mac, once upon a time..., I calibrated his aging CRT (only could crank 54 Cd/m2 at full intensity! I thought, his monitor was finished). Then a few weeks later, he landed a big contract and went to buy himself a completely new system; he called me in a few days later because, all of a sudden, all his "color-correct" images appeared too blue. No cataract in this story but I thought the parallel was relevant, he was looking, we could say, for some kind of "Adjustment layer"... / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Craig D. Sutherland via colorsync-users Sent: Thursday, January 16, 2020 12:53 AM To: colorsync-users(a)lists.apple.com Subject: Observation observations. I had New lens because of cataracts in each eye last summer. There was a two week interval between the two surgeries. I observed the color differences between each eye.. one original equipment to other the new improved version while waiting for the second upgrade . Very noticeable. I observed on target image on my Mac first through one eye then the other and created an adjustment layer that appeared to 'correct' so the images looked similar through each eye as I turned the layer on and off. I realize that is a completely bogus methodology, but it was interesting and fun. Craig Sutherland _______________________________________________ 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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Observation observations.
by Craig D. Sutherland 16 Jan '20

16 Jan '20

I had New lens because of cataracts in each eye last summer. There was a two week interval between the two surgeries. I observed the color differences between each eye.. one original equipment to other the new improved version while waiting for the second upgrade . Very noticeable. I observed on target image on my Mac first through one eye then the other and created an adjustment layer that appeared to 'correct' so the images looked similar through each eye as I turned the layer on and off. I realize that is a completely bogus methodology, but it was interesting and fun. Craig Sutherland

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Monitor Gamma
by graxx＠videotron.ca 16 Jan '20

16 Jan '20

Im doing some exploratory experiments with regards to gamma. I know its far from gamut discussions. Its a lot more complex subjects than I thought. I confess I got drawn in this exploration in the wake of 8-bit vs 10-bit capabilities. I just want to share some progress. In the following Excel sheet (yes, Excel is a great color management tool), youll find two tabs, at the bottom. The first one is labeled Step=32 and the second is Step-4: https://1drv.ms/x/s!AkD78CVR1NBqktUgigDMsTGPE-U6zw?e=FVTqrn Id suggest you start by the Step=4 tab. Towards the top left, in the range B12:B20 are the RGB values I sent to my monitor. In the range C12:C20 are the measured Luminances (Y) of the corresponding RGB values in VisualStudio (C#), whereas in the range D12:D20 are the measured Luminances of the of the corresponding RGB values as displayed in Photoshop. Basically, I generated the chart that sits in the columns T to W in code, to test some hypothesis about gamma, and thats when I noticed a difference between the chart viewed in my application development environment and a PNG version of the chart viewed in Photoshop. (I did not share that PNG but it is the same as what I created in Excel, in all these 9 rectangles, sitting between columns T to W. In the process of experimenting with gamma, I wanted to see what those rectangles would look like had they not have any gamma correction, in other words, in terms of equal brightness increments. The theory goes (as far as I read) that perceived brightness follows a power law. Fair enough. So youll see I build two charts, one which shows the measured Luminances gathered from VisualStudio and Photoshop, and the other, the theory behind gamma encoding and gamma expansion, as I found it called. Sorry, I did not give that second graph a title. And there is a screen capture below it. Now, if you turn your attention to the step wedge sitting between column X and AA, youll see that its the same 9 rectangles but filled with different RGB values, gamma expanded values which, in theory, ought to look equally spaced, perceptually, in terms of brightness. Arrived at that point, it occurred to me that, because of gamma expansion, RGB 32,32,32 becomes RGB 100,100,100? I thought, arent we loosing a whole lot of levels to this gamma expansion? I mean, is there life between RGB = and RGB 100? So wanting to address this question, I turned my attention to creating a step wedge with finer increments, Steps = 4, thats the second tab. I think its relatively easy to follow at this point, basically studying the relationship between Input RGB codes values and their appearances with and without gamma expansion. On the left, between columns B and E, are straight RGB values, from 0 to 256, in steps of 4. Between columns J and M are the same rectangles but gamma expanded. In Excel, you could zoom out like hell, to 25%, to see the whole gradient. Now, I was somewhat reassured by this study of gamma in steps of 4. But I was still not happy with what was going on below 4? I mean, look at the relatively large jump between RGB 4 (that becomes 39) and RGB 0? Thats not the same jump as the rest of the scale? And somehow, I got the impression that Im losing depth or contrast to this gamma scheme, in terms of tone range? So I created yet another series of rectangles, in columns S to Z where I went as small as in Steps of 1, from RGB 0 to RGB 16. And even at such small increments, with a gamma of 2.2, there is still quite a jump between RGB 0 and RGB 1, which becomes RGB 21 in a gamma expanded world. Call me nuts but I still was not satisfied with the result of this experiment? At one point, I toyed with the idea of what if I was to lower the gamma value down question? Like 1.8 or 1.5 or, gasp!, 1.0? Well, this this monitor, there is a utility called Multiprofiler that allows changing the monitor gamma on the fly. So I was off to the races and, voilà!, gamma of 1.0, no recalibration, nothing. I cant post how the image appeared on my monitor here, youd have to have your monitor set to a gamma of 1.0 as well. But suffice to say that, all of a sudden, there was no jumps anywhere throughout the entire scale, no blocked shadow details, perfect 1:1 tonal mapping, if I can dare say. Of course, all the windows, dialogs, UI looked completely washed out and there is nothing anyone can do about that, thats just the nature of Windows and MacOS as well. There is a underlying system gamma of 2.2 so that all controls and UI are designed to work at 2.2. What Id like to see is having a monitor profile created with a gamma of 1.0 while the system gamma would remain at 2.2, if that was ever possible. I realize with this crazy idea of gamma = 1.0, Im beginning to sound like Timo Autokiari, for those who remember, many years ago At this point, the question I have is, does gamma calibration matters? For color management? I know, in my humble and perhaps naïve practice, I never questioned the need for gamma calibration, whether 1.8 or 2.2, depending on religion. But in terms of preserving image quality, whats the trade off? The majority of LCD monitors sold today emulate in circuitry how the CRT response, thats a given. My cheapo SAMSUMG 2693HM has three choices of Gamma in its OSD, Gamma mode 1, Gamma mode 2 and Gamma mode 3 no documentation, no numbers of any kind to be found in the OS. But, clearly, according to my measurements, one of these modes emulate a 2.2 gamma encoding. So that, with a 2.2 system gamma such as in Windows and on the Mac, the whole world is not going to be crumbling down the moment the monitor is plugged in the video card. So, gamma is an evil that cant be avoided. Monitors manufacturers play by it, television manufacturers play by it. You would think that, the day LCD were invented, we would abandoned the CRT gamma for a linear response? But I understand the need for legacy. It makes me think what happens when CTPs first entered in prepress, everybody was wondering the same thing: What should we set our plate calibration to?, now that they had the possibility of making 50% dot in Photoshop print 50% on the plate. It took a while for that innovation to digest in the industry Also, as I discovered, gamma is also built-in digital images. So that, the way I understand it, JPEG has a built-in default (maybe hard-coded?) gamma value of 2.2. So, its everywhere. It cant be turned off. Now one of the lingering question I have is how does this gamma encoding translates to ICC profiles? Are there still these limitations in terms of usable device level values or are we free to do as we want? I mean, between RGB 0 and RGB 1, whether its coming from an ICC profile, with a gamma of 2.2, or straight from a 2.2 gamma-calibrated monitor, isnt there the same limitation? Which makes me want to study what happens in a 16-bit per channel RGB world. My initial foray in this brave new world showed me that the relationship between input RGB levels and measured Luminances are *linear* -- yes, linear, at least at a monitor gamma of 2.2, in Windows. Thanks for bearing with me this far / Roger

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Effects of lens implants on color vision (Was RE: Human color vision)
by Wayne Bretl 16 Jan '20

16 Jan '20

Some personal observations on lens implant effects on color vision: Photochromic eyeglass lenses absorb ultraviolet and deep violet. Before I developed cataracts, they appeared to have a slight amber tint, especially noticeable in natural outdoor light, but also by placing them on a piece of white paper under artificial light. They would change the saturation and hue of blue skies. As my cataracts and lens browning developed, I lost the ability to see the amber tint, as everything was subject to an even stronger yellowish filter. After each eye received an implant (six years apart) it was possible to see the amber tint again in that eye. There is a choice of clear implants or UV absorbing implants. UV implants could be identified on the info card they gave you, as the type number had "UV" appended. I made sure to get UV absorbing, as I suspected they would most closely match my vision prior to browning of my natural lenses. This was confirmed in a striking way by a colleague of mine who accidentally got a clear implant in one eye and a UV absorbing one in the other. He had a beige winter coat of a cotton/synthetic blend, with pure synthetic knit collar. Viewing through the clear implant, especially in natural daylight, he reported that the collar looked purple, while it matched the main material much more closely through the UV implant. I verified his observation of only a slight mismatch with my UV-absorbing implants. I also noticed something about white point adaptation during the time I had only one implant. Even after a long time of adaptation in a given environment, closing one eye and then the other showed a definite yellow shift in the untreated eye compared to the one with an implant. I did not expect this, thinking that each eye would adapt to the same overall balance. Despite the difference, the sense of what objects in the field of vision were white was equally strong in both eyes. I take this to be an indication that the process of identifying white is separate from the process of seeing a white object as a particular color. (This yellow shift is gone now that I have implants in both eyes.) -----Original Message----- From: colorsync-users <colorsync-users-bounces+waynebretl=cox.net(a)lists.apple.com> On Behalf Of David Scharf via colorsync-users Sent: Tuesday, January 14, 2020 6:54 PM To: colorsync-users(a)lists.apple.com Cc: David Scharf <electronman(a)roadrunner.com> Subject: Re: Human color vision You'll finally be able to see violet again!!! DAVID SCHARF PHOTOGRAPHY *DAVID SCHARF * On 1/14/20 9:25 AM, Roger Breton via colorsync-users wrote: > Bob, > > Call me nuts, but I'm actually looking forward to the day I'll have a cataract removed for the very reason you mention, that experience of looking at the world, all of a sudden, *without* yellow filters. I read the same account as you described, in the color literature, that the sky takes on a stronger vivid shade of blue and so on. > > All I know about the Standard Observer is that it was made of two groups of men but I have no details on their age... I guess they had "normal color vision" 😊 > > / Roger > > -----Original Message----- > From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Bob-BTY via colorsync-users > Sent: Tuesday, January 14, 2020 10:42 AM > To: colorsync-users(a)lists.apple.com > Subject: Human color vision > > Many people don't seem to know that the lenses in the human eye start going yellow with age. By the age of 50 most people are looking at the world through yellow filters! I experienced this when having a lens replaced because of cataract. The new plastic lens was clear, and when I came out of the operating room, I could see that the dresses of the nurses (that were grey/white stripes before) were now blue/white when I looked at them with the new lens. With the yellow lens in my other eye they were still grey/white! A blue sky was now qite vivid with the new plastic lens, not so with the old yellow lens. I played about with Wratten filters to see how yellow my original lens was, but sadly I can't find the details any more, and nnow have two clear plastic lenses. I wonder how old the 'Standard Observer' was? > > Bob Frost > > _______________________________________________ > 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 > > _______________________________________________ > 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/david%40scharfphoto… > > This email sent to david(a)scharfphoto.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/waynebretl%40cox.net This email sent to waynebretl(a)cox.net

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RE: Effects of lens implants on color vision (Was RE: Human color vision)
by graxx＠videotron.ca 15 Jan '20

15 Jan '20

I see. I don't wear glasses -- yet. I thought these were "gimmick" types of glasses. I was wondering if one could "buy" glasses that would have no optical power with just the "UV coating" then? I guess anything is possible... Thanks / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Andrew Rodney via colorsync-users Sent: Wednesday, January 15, 2020 1:48 PM To: 'colorsync-users?lists.apple.com' List <colorsync-users(a)lists.apple.com> Subject: Re: Effects of lens implants on color vision (Was RE: Human color vision) > On Jan 15, 2020, at 11:40 AM, Roger Breton via colorsync-users <colorsync-users(a)lists.apple.com> wrote: > > Never heard of "UV glasses"? > Would anyone have a link? Really? Every time I purchase glasses, I’m asked IF I want UV coating: https://www.framesdirect.com/knowledge-center/uv-coating <https://www.framesdirect.com/knowledge-center/uv-coating> Andrew Rodney http://www.digitaldog.net/ <http://www.digitaldog.net/> _______________________________________________ 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: Effects of lens implants on color vision (Was RE: Human color vision)
by graxx＠videotron.ca 15 Jan '20

15 Jan '20

I suspect this is one of the reason chromatic adaptation studies 'worked'. To my humble knowledge, they were done in that fashion, with one eye looking at some stimulus while the other looked at an entirely different one. / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca(a)lists.apple.com> On Behalf Of Wire ~ via colorsync-users Sent: Wednesday, January 15, 2020 2:07 PM To: 'colorsync-users?lists.apple.com' List <colorsync-users(a)lists.apple.com> Subject: Re: Effects of lens implants on color vision (Was RE: Human color vision) On Tue, Jan 14, 2020 at 18:23 Wayne Bretl via colorsync-users < colorsync-users(a)lists.apple.com> wrote: > > I also noticed something about white point adaptation during the time > I had only one implant. Even after a long time of adaptation in a > given environment, closing one eye and then the other showed a > definite yellow shift in the untreated eye compared to the one with an > implant. I did not expect this, thinking that each eye would adapt to > the same overall balance. You mean you felt the one eye showed yellow compared to white, as opposed to the other showing blue? It's said that the roots of the term gamut are in 15th century music with the term referring to lowest G in a complete scale. (Quick digression into idea of a musical scale as a range of distinct and countable notes) Do you think that there's such a trait as musical "perfect pitch" but for color? _______________________________________________ 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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