Color Correction

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.

Original contents copyright 2017 by Michael C. Johnston and/or the bylined author. All Rights Reserved. Links in this post may be to our affiliates; sales through affiliate links may benefit this site.

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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."

Comments

[Andy Umbo]

I used to work in a studio with their own color lab, back when I was in highschool, and the QC manager was adamant that anyone's color perception and ability to judge subtle differences changed throughout the day, and throughout the week! That stuck with me.

Re the following:

"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."

This must be why I have a tendency to dislike Japanese color negative films, which seem to me to bias "pink" compared to Kodak film, which seem to bias "amber".

It's also interesting because the "81" range of filters, which we religiously used on Ektachrome film (even using an 81 outdoors, and an 81A under strobe), is really a combo filter of red and yellow, and not a "Pure" filter like R, G, B, C, M, Y. Made solely by Kodak in the beginning to "improve" the look of skin tones in their films.

You've always had to be careful to buy 81 series filters from the correct source, because for a while european filter manufacturers were selling their CR series filters as 81's, when they really weren't. I remember putting a B&W allegedly 81 filter down on a light table back in the 80s', next to a Tiffin, and one was "pink" and one was "amber".

[Kenneth Tanaka]

If Kodak actually goes forward with reissuing Ektachrome many TOP readers will get plenty of practice on their "color correction" skills.

,-)

[Paul Whiting]

I had my cataracts removed a few years ago, one at a time. During that interim between removals, I too noticed a distinct color difference between the two eyes. And my black and white photos (which I shoot mostly) had increased "pop". I posted this observation on a website somewhere and the moderator said when color questions came up he might, respectfully, start asking the questioner if s/he had had cataracts removed. So, yes, an excellent conversation starter Mike, thanks for bringing this to the attention of your readers.

[John Krumm]

I've aways thought our brains have surprisingly good white balance correction, especially handling mixed lighting with ease. I imagine with older eyes it will compensate up to a point, but of course it's only in the brain, and not in tune with everyone else.

I tend to do exactly what you suggest, adjust a photo to neutral and then usually warm it slightly from there. Occasionally, with skin tones, I'll just look at the skin and try to ignore everything else. I've found the camera profile sliders can help here (in Lightroom and ACR).

Thanks for the color correction tutorial. Many of us haven't had much of an art education and are kind of winging it, so this stuff helps.

[Dennis Mook]

Mike,

I've been printing color since the late 1970s and I found it extremely difficult to learn how to print color well. Colors would be "off" to my eye and it took a long time to figure out how to correct them. Corrections weren't as they would seem. Also, I learned that you better have your luminance correct before color correcting as brightening or darkening an image would also cause a color shift. Luckily, I had a good friend who owned a professional photo lab and he taught me a lot about how to color correct. Again, there is a lot of subjectiveness to what one thinks is "correct" color.

On the other topic, I turned 65 last week and have worried about cataracts and the color cast and impact they have on seeing the world in color. Luckily, my opthamologist told me last month that the very little cataracts that are just starting to form won't impact my vision for a long time. But I worry about getting the color right on my images, just the same.

If clear, crisp eyesight wasn't impacted by cataracts and it only resulted in a yellow color shift, I would go back to my first photographic love, black and white, and not worry about it.

[Paul Whiting]

PS: I had not been happy with the overly warm tone in my paper and mat board either... suddenly these became cooler.

[Brian Taylor]

Good luck with your new vision. I've never thought of colour correction, or indeed post-processing as fun because of an issue you don't mention -colour blindness!

For very many, especially men I believe, this seems to manifest in an inability to differentiate certain pairs of colours. I first became aware of it as a trainee town planner, long ago (I'm 69 next week) when a land use map I'd coloured in turned out to have lots of mistakes. I was mortified. My supervisor brought out a huge colour chart - a vertical column with very subtle gradations- and it turned out that everyone in the office had areas where they couldn't differentiate adjacent tints.

For me, red-green-brown are the most tricky areas, though the effect is subtle. Its presumably also tricky to differentiate this from colour bias/preference? Hence, perhaps, the much aired differences of opinion in the micro four thirds firmament over 'Panasonic versus Olympus colours'. (a popular 'versus' issue. Personally I find what many people do with the warmer Oly pallete, or indeed with Fuji's veliva simulation, almost impossible to look at, -but have always been clear that this should be a a horses for courses question.

I shall ponder that colour diagram, then perhaps I'll be able to work out what cyan is :)!!

[Michael Perini]

Mike, here is a good place to start:http://www.xrite.com/hue-test
This is not perfect because every viewing screen ( especially older laptops) will be different, and most graphics cards are still 8 bit color depth.
But they certainly are helpful , especially if you repeat it from time to time.
I've been doing it for 5 years and always manage to score high but not perfect- always get 1-3 comparisons wrong. If I suddenly began to get 5-10 wrong I would know Something changed -my eyes or my screen. so I could investigate further.
If you had the latest display driven by a wide gamut 10 bit graphics card, it would be very accurate.
I suspect the latest Macs which sport the P3 color gamut graphics cards and Retina displays would be quite accurate.
Better still would be a NEC Or Eizo10 bit displays driven by a 10 bit signal path (hardware & software) would be the best we have at the moment.
I've been hoping for a Mac 'midi' small flash ram boot drive space for a second data drive and graphics card and ram capacity suitable for being a small graphics workstation. You can do that with a PC quite easily. I'd like to do it on a Mac.

[Alan]

Took me years of practice to get good with color, Now I think all my old stuff looks wretched.
This last one is ok
https://www.facebook.com/CoastalPhotographyByAlanHoelzle/photos/a.304702226304435.73773.304697196304938/1199684783472837/?type=3&theater

[JF]

I got a 4 on the xrite test. I'm pretty happy with that being I'm just over 60.
I wish you had posted this a few weeks ago. The wife insisted we mix some paint. I knew it wouldn't go well. It was too blue... should have just added a little yellow. Oh well.

[David Babsky]

My colour vision - like Brian's, above - is also hopeless, with an inability to distinguish between red, green and brown. (My Beloved and I went to an Emil Nolde exhibition a few years ago, where everything - to me - looked simply like mud.)

In the spring or summer we go to Valley Gardens, near Windsor (UK) to see the azaleas and rhododendrons opening, but I can't see red flowers against green leaves. It's only when she carefully points out which are the flowers that I can then distinguish them from the leaves by their shapes, and can then force myself to see them as 'red'.

We went to Japan back in November 2014 to see the Acer trees turn red ..but, of course, I just couldn't see that, except on the rear screen (and electronic viewfinder) of my camera(s). On the rear screen of the Oly E-M1 I could clearly see the bright red leaves, but in "real life" they looked exactly like the adjacent green leaves. The difference was clear as day on the camera screen!

Like Ken Rockwell, I turn up the 'Vivid' setting of my cameras to about +2 or even +3, and that - for me! - makes my photos come alive! I like my photos to be not simply representations, or reproductions, of what's in front of the lens, but also to be big chunks-of-colour-for-their-own-sake. Though what I see may be quite different from what others see.

(I did have a lens replaced ..in just one eye.. and it's now very sharp! But I don't see any difference in colour between that and the 'normal' eye. But then perhaps my colour discrimination is so poor that I simply couldn't anyway.)

To see reds and greens in their 'proper' colours, I have a couple of 99p (99¢) pair of cheap sunglasses which DO provide a clear differentiation between red and green. And for night-time (boat) navigation I use a couple of little red and green hold-up-to-the-eye plastic filters called "Sea-Key", one of which which passes red light but not green, and the other vice-versa.

I'm hopeless at colour printing, as I have no idea - it's like being tone deaf - of what colours ought to look like, although I do have my own preferences. But as my blue and yellow vision seem to be OK - from what I understand - I LOVE switching a camera's WB to 'Tungsten' just after the sky's gone dead black, and creating photos with a dee-eep blue (or maybe it's purple) after-dusk sky! That gives me a real kick!

Apparently, colour-blindness affects about 1 in 7 men - but not women, who are the carriers of colour-blindness, like haemophilia - and I'm always hugely in awe when other people can detect the minutest differences in shade, or tone, or whatever it is, between colours, and I can see no differences. (My wife can spot a red buoy at 500 yards; I can see a dark speck, but cannot detect any colours further away than about 100 yards, and certainly not red. On the other hand, my aural acuity is terrific, and so am continually distressed by awful quality music in restaurants and bars. Sometimes I think it may be better not to have fine discrimination.)

[Rob Griffin]

About 20 years ago I was looking through my Nikon F3. I was trying to determine if a diopter would work for me so that I didn't have to wear my glasses while shooting. I tried each eye to see if one eye was better than the other.

I was really surprised to see that with my left eye color was noticeably cooler than my right. I guess the brain easily manages the difference. After reading this, I checked again with both a OVF and EFV. My left eye still sees cool and the right eye sees warm. No real point here, but I am still amazed that our eyes and brain work all this out somehow.

[Geoff Wittig]

1) I started printing photographs using scanned slides around the late 1990s, and color correction was torturous. Each slide film had its own intrinsic color bias. Time of day and color of light at capture added another wrinkle. The scanners of the day generally added their own quirky deviation depending on the age and type of light source they used. And early pigment inkjet printers were notorious for narrow color gamut and horrendous metameric failure, meaning prints shifted color balance spectacularly under different light sources. Things are vastly better these days with digital capture and modern inkjet printers, but it's still not simple. Photoshop provides lots of nominally objective tools for color correction, but in the end it's always a matter of judgement and salting to taste.

2)Color correcting photographs has been more intuitive and logical for me since I started painting landscapes. Color mixing oil paint teaches you the color wheel in the most explicit way possible. If you want to make a green warmer, you have to physically add more yellow or orange pigment to it. Since most colors in nature are pretty subtle, you spend a lot of time gently nudging neutral colors in the right direction. Adding cerulean (blue with a green bias) gives a very different result from adding ultramarine (blue with a red/purple bias). I find it really does carry over to Photoshop and using sliders or curves adjustment layers.

3) Photoshop's most visually intuitive color correction widget, the 'variations' tool, provides a ring-around of color variation thumbnails surrounding the original image. But the implementation is terrible; it provides only a fixed, universal degree of variation; clicking on a variation shifts the whole kit 'n kaboodle in that direction by a fixed amount. No sliders, no adjustability, no subtlety at all. Just a tease. (Unless Adobe changed it recently; it's so useless I haven't tried it in quite a while.)

4) I'm also approaching 60. I don't have significant cataracts, but my two eyes have very different color biases. Through my (dominant) right eye things look significantly warmer than they do through my left eye. Does this affect my judgement when I'm using Photoshop on a 28" monitor with both eyes open? Damned if I know. But it's making me think.

[hugh crawford]

Human color vision is pretty weird. It's really good at differentiating greens, and we imagine that there is a color called magenta.

It's equal parts physics, philosophy, and physiology.

Anyway, the corneas are acting like UV filters. Remove them and you can see in ultraviolet. If they were shifting the color balance you would never notice.

Interesting story here

http://www.downloadtheuniverse.com/dtu/2012/04/monets-ultraviolet-eye.html

I haven't tried the app mentioned because I haven't got an iPad handy but it sounds interesting too

https://itunes.apple.com/us/app/color-uncovered/id470299591?mt=8

[john robison]

Don't know about color but in dim light my left eye sees very much brighter than my right eye. I'm left eye preferred and have been told my right eye has more developed cataracts than my left (I'm 67). Neither eye is bad enough to consider replacement lenses yet.

[Romano]

Mike, on the subject of cataract and color-vision --- have you seen this post?

http://www.komar.org/faq/colorado-cataract-surgery-crystalens/ultra-violet-color-glow/

I thought it was fascinating.

[Andre Y]

I've been slowly slogging through Dan Margulis's Modern Photoshop Color Workflow, and he advocates using Lab color space to judge color neutrality. The "a" dimension is magenta-cyan, and the "b" dimension is blue-yellow, while "L" is pure brightness (ie. B&W from desaturation).

Basically, you use an eyedropper and look at known reference points in your photo to see if it's too much of one thing. For example, skies are blue, so their b-values should skew negative, but they're probably not green, so a-values should be zero or perhaps a bit positive. Adjust accordingly.

It's not hard to do in either PS or Lightroom, as both allow you to look at color values in Lab space instead of RGB, and it's far more intuitive than trying to figure out what a particular RGB value means and how to correct it. Photoshop is of course the better way to correct things as you can create curves layers that only affect the color component of a photo, but it's useful in Lightroom as well to get the white balance right,

Margulis has a website with videos which demonstrate his techniques, and it's worth checking out. Specifically, look at the chapter 3 video on this page titled "The Initial Color Evaluation": http://www.moderncolorworkflow.com/private-resources

For an artistic take on color combinations, check out Nick Fancher's work. He's been combining the outputs of gelled speedlights to create very interesting portraits: http://nickfancher.com/

[Stan B.]

I'll spend hours, days, sometimes weeks getting the tonal values in B&W to my liking. I click Color Correction in Elements and... done!

PS- On rare occasions I'll apply a warming filter.

[Thomas Rink]

I find that it's sometimes difficult to become aware of a tint, as the effect can be rather subtle. A clue is when a picture just won't work, even though I can see its potential. Experimenting with the colour balance sliders in this case often brings an "Eureka" moment. I've once read that while formal qualities of a picture are judged mostly by intellect, its colors hit us on an emotional level. I believe that this is true.

Best, Thomas

[Dillan]

I'm colour blind, and I admit: 'colour correction' is a big mystery to me. I muddle through, and I think I do an alright job, but I can never be sure. Most of the time, it's not a problem until I'm shooting people. If I'm outside, I go with more or less factory settings. I'll saturate and desaturate to taste, but that's about it. If I shot the photo on a cloudy day, I set my Lightroom to 'cloudy,' and poof! It's colour correct!

Artificial lights can be vexing, especially if I mix flash and ambient light. If that's the case, I nearly always make a nice black and white photo, and that works well for me.

In any case, I shoot merely for my own enjoyment. I found this article very interesting. Thank you again, Mike!

[Fred Salamon]

After cataract surgery many find that they need glasses for reading/computer work. Be aware that the anti-reflective coatings on eyeglasses can cause a colour shift. This colour shift may be a factor when soft proofing your images for printing.

[Matthew Liggett]

This reminds me of (apocryphal?) stories about Zappa re-mastering most of his albums in old age. The story is that, like many aging musicians, Zappa had diminished hearing in the high frequencies, so the remastered albums sound brighter. They sound bright to me.

We have "hearing aids" and even custom audiophile earplugs: https://earinc.com/.

But it raises--and we're now pretty far afield from cataracts, but still--it raises the question: Do our brains do the same kind of automatic "white balance" to compensate for changes in sound like they do with color? (White noise balance?)

Part of me wants to say yes: The song on the AM car radio is identifiably the same thing as the song at home on the hi-fi.

But part of me says no: We can still clearly hear the sound of the system in each case. It's much more obvious on its own than, say, color temperature is.

[Earl Dunbar]

I was fortunate to work at a professional photo lab where the manager of print production, a wonderful woman, was probably one of the best at "calling colour" who ever lived. (I have lost track of her - I hope she is sill with us.) When she went for training at Pako, she remarked that she could correct colour as precise as a half point.

No one believed her, but she was tested and the doubters found she was neither lying nor exaggerating. I can't claim to be as accurate or precise as her, especially now that it's been years since I have worked as a professional printer. But I was accurate to one point in my hay day.

Since I'm older than you, Mike (you know by how much - your "under guess" still amuses me) I would be interested to see how much my precision may have changed. I'm not sure how to test for that, but I'm forwarding this article to my optometrist for her review!

[John Willard]

The color blind talk reminds me of the November 2015 NFL game when both teams wore their colors instead of one team in white. Jets and Bills...Green and Red.
https://www.youtube.com/watch?v=WuTBs9stJCs

[Adrian Malloch]

The thing about colour correction is, it is a relative term dependent on your perception until you start measuring. Even then, the measured colour values are dependent on the underlying colour system – sRGB, AdobeRGB, and so on.
Here are two tips that will improve your colour perception, assuming that you at least have a half-decent monitor that has been calibrated and profiled. (Ok, so not everyone does, but if you produce photos for other people to view, then you owe it to your art to compose your music on a tuned piano, even though others attempting to play your score may very well have an un-tuned piano to play it on).
1st tip: Display your photos in Lightroom and Photoshop with a white background. That way your perception becomes calibrated to not only the colour, but the 'weight' of the photo on the page. This trick ensures you don't ever have to ask again,"Why are my prints always darker than on my screen"? Flick to a black background to check the darker values in your photo. As you flick back and forth between the two backgrounds you will immediately notice how much brighter and darker the photos appear. A lot of photographers say they prefer a black or dark grey background. Fair enough, but that approach is the equivalent to viewing the world with rose-tinted glasses. Do you want your photos to look good to you, or do you want your photos to be right?
2nd tip: Get iterative. That is, go way too far, then come way back, then keep going back and forth getting closer and closer until you find the point at which it doesn't improve. This works for colour cast, saturation, contrast, brightness and a whole bunch of things well beyond photography. (Not good advice for risk-taking teenagers but they'll just go ahead and do it anyway).
The thing with this trick is that it turns out we don't know what correct is until we see what way un-correct looks like. I could be onto a universal truth here.

[George Andros]

Two years ago my wife and I had cataract extraction/intraocular lens placement with a four week gap between the two eyes. We both experienced the restoration of true blue skies when the yellow cataract "filter" was removed from each eye. This is to be expected and has been experienced by many of our friends who underwent similar operations. For a photographer the operations turned out better than I anticipated.

[Richard]

As an addition, I will say that color correction in video is much more intuitive and probably a better way to learn because they use a color wheel with a control "knob" set in the center of the wheel. There are wheels for shadows, mids, and highlights.
To color correct, you use your mouse to push the control knob away from the color you have too much of and toward the one you want more of. The wheels look like this:
http://www.taoofcolor.com/wp-content/uploads/Resolve3WayCC.jpg

[Victor Bloomfield]

I tried the x-rite test, and -- much to my amazement -- got 0 (perfect)!
I'm 78, and my ophthalmologist says I have a mild cataract in one eye. But I guess it doesn't affect my color vision. My wife had much worse cataracts, and after cataract surgery the world looked much less yellow.

[Bob Rosinsky]

The topic of visual sensation and perception is one of my favorites. I've done a fair amount of research on human as well as canine vision.

In graduate school, I studied depth perception. I was drawn to the subject due to a neurological defect. The pathways from my optic nerves to the visual cortex didn't develop. Consequently, I have monocular vision. I see in two dimensions.

This led me to research how people with monocular vision compensate for their inability to perceive depth. ... First, I discovered that my left eye is biased towards red while the right eye towards blue. I tested a small population of stereo blind people and those with binocular vision. The folks with monocular vision were more likely to perceive the shift. Some subjects with normal vision were able to detect the red/blue shift, but they were the minority.

My opthamologist attributes this phenomenon to differences in refractive properties from one eye lens to the other. That is a reasonable explanation.

Still, the visual cortex in humans is adept at auto white balancing. Ergo, I'm not convinced the red/blue shift is entirely a matter of physics. I surmise it aids depth perception. The effect is subtle, albeit measurable.

I took the X-Rite color test today (google X-Rite color test). I used my Surface 3 screen and a wide-gamut Eizo monitor. My scores varied from one eye to the other. The test confirmed I see a red/blue shift.

[Steve Smith]

Color Correction

As I'm English... No, too easy!

[craig]

I've had cataracts for twenty five years now
they have progressed slowly and unevenly

my left (dominant) is like looking through a very strong warming filter while the right is almost unaffected

for years I've used a simple wink test when it really mattered, otherwise my images are just "ooh...your colors are so vibrant!"

[Gabe]

Always amazed at the broad spectrum of interests, experiences, and accumulated knowledge of TOP readers and commenters. Thank you Mike for stimulating conversations in areas where I never wandered before....like the above.

I believe that if TOP readers collaboratively applied our accumulated experience and knowledge, and yes, disagreement leading to discussion, we could theoretically solve many vexing common problems.

Or just go for coffee.

[Jeff]

Print display adds another layer of color management complexity to screen viewing. Display lighting can alter colors/tones that appeared fine on screen and in initial 'work prints'. This is where viewing booths and control of display lighting temperature can be useful. Even then, if one frames using glass, that too can alter color transmission. It's a complicated path for picky viewers, and who knows what others may see.

[Dave Polaschek]

In a funny(?) twist, I started using Sierra this week, and it has some transparency in the title-bar of Safari, so the yellow background of TOP shows through. I find myself grinding my teeth because something that's supposed to be gray now has a color-cast which is throwing everything off for me.

Any chance I can talk you into using something other than yellow, Mike?

[Sure Dave, if you'll volunteer to go back to about 50% of the illustrations I've ever published and replace that yellow with the new color. I estimate it would only take you about a month. --Mike]

[Brad McPhee]

I have an interesting book, Drug-Induced Ocular side effect by FT Fraunfelder. There are many drugs that affect your vision. Cataracts cause you to see more of a yellow tone and drugs like Viagra tend to cause you to see a blue tint. There are so many things involved it is amazing we get the images to look good at all!

[William Collins]

Enjoyed the article.

[Richard Geltman]

There's an interesting, slim, illustrated volume by John Berger-- he of "Ways of Seeing"-- called "Cataract." In it he describes in typical Bergeresque detail his own experiences leading up to and following cataract extractions of both eyes. Among many other observations he says, "if I try to sum up the transformed experience of looking, I'd say it's like suddenly finding oneself in a scene painted by Vermeer."

[Allan Graham]

Mike, I'm a serious user of LightZone, which I first encountered here, some ten years ago. In it colour balance is adjusted by moving a cursor around a colour wheel. Very obvious and intuitive, I find.

[Dave Polaschek]

I re-discovered the System Preferences > Accessibility > Display > Reduce Transparency preference again, and setting that makes the title bar opaque in Safari again. But I might take you up on that, um, offer for the next OS release, Mike.

[Khürt Louis Williams]

I'm 50 now and had replaced the "kit" in my right eye several years ago. It never occurred to me that I might have colour corrected my eyesight. After reading this I notice the difference. Wow!

The other eye will soon need an "upgrade" and I hope I can get a lens to match the one in the right eye.

[Anthony Shaughnessy]

I just tried your suggested technique for removing casts, it worked quite well - thanks. I usually struggle to get the green/magenta balance right in Lightroom. Your technique helped.
Anthony

[HABS HAER Photographer Stephen Schafer]

Mike, I’m an architectural photographer and while our eyes do often do a good job of auto color balancing – even in mixed light – the color rendering of the lights in your studio is also a big factor. If you photograph or print indoors you may have noticed all lights are not created equal. For your readers that don’t know what CRI stands for (Color Rendering Index) they should brush up on what their room lighting contains before attempting to color balance in it. With the move from inefficient incandescent (CRI 100) bulbs to compact fluorescent (CFL) and LED versions for efficiency, we have given up a substantial part of the color spectrum we used to take for granted.

The bulb manufacturers are not required to list the CRI on the box or the bulb. I have found that High-CRI is now being used as a marketing “feature” so if you are buying a new light and the CRI value is not listed, it is almost certainly less than 89 and may be less than 80. And you might as well put your cataracts back in if you are printing in that kind of light.

Of course if you are photographing a new building and the architect has specified the required energy efficient lights, you are in for a mess of unsaturated colors, and mismatched Kelvin temperatures. Add in the energy-reflective and UV-blocking window films and green glass and you’ll have a smorgasbord of color crossovers to deal with in post.