I got a marvelous comment yesterday from Peter Conway that deserves its own post, about the color-correction of aging eyesight (he and I are the same age):
Towards the end of 2016, I got a couple of new lenses, but they weren't Nikon or Sigma Art—they were from Abbott Labs, and replaced the "factory-issued" lenses which had cataracts (I'm 60 in two weeks).
After the first eye was done, I was shocked at how blue the world looked through that eye—until it occurred to me that the issue was likely that the world looked unusually yellow through the other eye. My ophthalmologist assured me that the Abbott lens had the truer colors. The three weeks between surgeries was an interesting period, with each eye vigorously disagreeing with the other on how things looked.
Now that both eyes are done, the world does look different, but more subtly than I would have thought after the first eye. It turns out that "Carolina blue" is actually blue to me now. And the green pill I was taking, which the pharmacy said was blue—well, it turns out the pharmacy was right.
I've started looking at some of the color prints I've made, and am pleasantly surprised that some actually look better than before—less muted than I had been seeing them. Others, though, are a bit over the top and will need some re-work.
So my question to you is, given all the color management technology available—profiles for our monitors, profiles for our printers, profiles for all sorts of different papers—is there any way to color manage our eyes? That's a lot bigger variable than I'd realized even two months ago.
I can't begin to answer his question, although I have what I believe is an example of older eyes leading a photographer astray—at the end of Ansel Adams's life, the art dealer who had made him rich, Harry Lunn, prevailed upon him to make "The Museum Set," a master edition of his greatest masterpieces, destined for museums. Which he did. Unfortunately, Ansel was very dissatisfied with then-current photo papers, and he also appeared to be having vision issues—the "Museum Set" prints are among his least satisfactory from a printmaking standpoint, nowhere near the spectacular balancing act of his best prints.
Basic color correction
By the way, to learn color correction, it's necessary first to simply memorize the major RGB complements (the three pairs of two opposites per pair), then teach yourself to see what color a picture has too much of. At that point, you know what to add.

RGB color wheel
Blue is the opposite of yellow, red is the opposite of cyan, and green is the opposite of magenta. So if you see just a little too much green in a picture, you know to add a little magenta. See too much cyan, add red. Thinking of it in terms of what color to add will gets you out of all sorts of trouble. And it's much easier to detect what's there than what's missing.
I've mentioned before that many experienced color printers have a "color cast preference"—a color they favor just slightly. I favor prints that skew just a skosh red; Ctein told me he favors cyan (which I believe is unusual—he's the only person I know with a cyan bias). Knowing your color bias preference helps you to keep it in check, for one thing! I'm always cautious about whether I might be adding too much red.
A little secret
Another issue with color correction is that most people have wildly varying tolerances for casts, and here's a little secret. While most people don't like even a little bit too much of certain casts like cyan and magenta, human beings in general have a huge liking for yellow, AKA "warmth." Whereas you might not even be able to get away with two or three points too much green or cyan, you can add five or ten points too much yellow and you might still be all right. (The theory is that "golden hour" sunlight is yellow and inherently pleasant to us.)
That's why the "color temperature" slider (blue-yellow) is so central to most editing programs. And it's also why yellow gets newbie color printers / post-processors into trouble they sometimes can't get out of. Why? Because judgement with yellow is tougher to "feel" correctly—everything from neutral to way too yellow might look subjectively equally good, just different. So which way do you go? Without experience, it's easier to get confused.
My preference was to teach people to always to get the color temperature, the yellow-blue pair, as neutral as possible first—with reference to your memory of the original scene—which in turn allows you to see other color casts more easily. Correct those, and only then add a bit of yellow back in to see if more warmth is preferable to you.
For practice, go to any photo site, the more amateurish the better, and start looking for pictures with color that looks "wrong." Figure out what it has too much of, and thus, what you would need to add. There's nothing stopping you from actually doing it, either—that is, nothing stopping you from downloading strangers' pictures and color-correcting them for your own practice. As long as you toss your copy out afterwards and don't actually nick their work.
Color correction is fun, and, as any experienced color printer will tell you, helps you see color in pictures much more readily* and accurately, too—and enjoy it more when you see photographs with color that "sings."
Mike
(Thanks to Peter Conway)
*To me, for example, the second picture in the "Two-Hat Weather" post, of the frozen waterfall, is a riot of colors! :-) Look at it again and notice the rust browns in the rocks and the cerulean in the ice.
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(To see all the comments, click on the "Comments" link below.)
Featured Comments from:
Ben Rosengart: "Very interesting, Mike. I just forwarded this to my dad. He claims he's no good at color correction, but I maintain he just hasn't put in enough hours."
Stephen Cowdery: "Looking at the color graphic, I thought that my green perception was faulty—the green and chartreuse triangles appeared to be exactly the same. I opened the graphic in Photoshop and checked the info reading: R-0, G-255, B-1, for both segments!"
Mike replies: Sorry. I start with a Wiki graphic of unknown provenance, convert it to sRGB, and then submit it to the mercies of the TypePad blog software (which does change things). By that time it's far from calibrated—really just a rough illustration of what it's supposed to represent.
Here's another, possibly easier way of visualizing additive color:


Each primary color (R, G, or B) is the opposite of the smaller overlap opposite it. (Top image courtesy Wikipedia.)
The colors still aren't quite right but if you accept that these are just illustrations you'll be all right. The key thing to emphasize is just that you have to memorize the three pairs of opposites. Then, whatever color you see too much of in a picture, add more of its opposite.
Ranjit Grover: "The 'factory-issued' lens turns yellow, opaque and rigid with age. That is the reason it has to be replaced. The automatic white balance in our brain does a good job and we do not see the effect of the yellow lens as long as both of them are of the same color depth. But once one of them is replaced with a plastic lens we see the difference. The plastic lenses too are slightly yellow, but not as much as the 'factory supplied lens' with cataract. What one person sees as yellow may not the same as another one sees. There is no way one person can tell another person exactly what he sees or hears or tastes or feels. Neuro scientists call this problem 'qualia.' Qualia comes alive when we have two different lenses in our eyes. Or when one ear is defective. Probably qualia is what causes our individual color preferences."
Herman: "I'll stick to black and white."
Mike replies: That's even harder! But no worries, you're good at it. :-)
Ken N: "I use reference pictures to 'calibrate' my eyesight as I work. It was a trick I learned many years ago with audio editing."
Mike replies: That is indeed a very good trick. It helps a lot with B&W, too (apropos Herman). I used to keep a manilla folder of reference B&W's in the darkroom—eight to 12 examples of "perfect" tonality—and if I felt my perception getting a little off-kilter, I'd just look through them. Naturally I still remember some of those pictures!
MarkR: "I'm reminded of Claude Monet, who redid some of his water lily paintings after he had cataract surgery. He was reportedly upset that he had painted them too red."
Mike replies: The story of Monet's struggles with his vision in later life is very involved and complicated; one thing that stuck with me is that he apparently wanted to convey in his paintings how he saw, because it was very lovely, but he couldn't see well enough to paint it properly. At this point I'm not sure if that's some species of fact or just my interpretation....
Stephen F Faust: "Re 'The key thing to emphasize is just that you have to memorize the three pairs of opposites. Then, whatever color you see too much of in a picture, add more of its opposite.' ...Which explains why Lightroom has a blue/yellow slider and a green/magenta slider, but why doesn't it have a cyan/red slider?"
Mike replies: Because technically you can do everything you might need to do with just the blue-yellow and green-magenta sliders in ACR. Increasing both blue and yellow at the same time (moving both sliders to the left) is the same as adding cyan, and increasing both yellow and magenta at the same time (moving both sliders to the right) is the same thing as adding red. Try it. The problem with that is that it's not as intuitive as having three sliders in terms of looking at the picture, evaluating it, and knowing what to do, which is why in Photoshop I would suggest doing color correction in Image > Adjustments > Color Balance, which has three sliders.

Presumably Lightroom has the same three sliders somewhere too? (Or is it more automated in LR?)
John Krumm answers Mike: "To answer your question, Lightroom doesn't have that color balance tool. Lightroom adjustment options mirror ACR. I'll have to try it; it will give my neglected Photoshop CC something to do."
Mike replies: That's weird. I reviewed the correction options in LR using Adobe's online instructional videos, and looks to me like Develop > HSL falls into the classic trap of automated tech: it makes color correction—better make that "color enhancement"—easier to carry out, but more difficult to understand.
Richard: "Color management of your eyes is really just knowing about their shortcomings and working within them. The biggest enemy, according to my research, is your own brain. That's why it's best to only look at something you want to color correct for a few seconds at a time. After that your auto color correction kicks in and you won't be able to see what's wrong anymore. And eat your carrots, of course. The normal caveats apply as well, paint your walls a non-pigmented grey, keep light levels low, and don't work when you're tired because your brain just won't be up to the job. The one other thing I would say is that there is no shame in using a ColorChecker to create a custom profile—especially when you shoot in weird mixed lighting conditions. Using a color checker or a calibrated grey card is like sharpening up your saw and planing your boards before you start a woodworking project. It frees you up to be more creative because you're starting from a neutral place."