Chasing perfect color, and common myths about white balance

The previous article on the inexact science of color and emotion dealt with why color was important, and how we can use it as a tool to alter the mood and emotional response of the viewer of our photographs. This article explains how we get there.

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Sandwiches. Did you know greens are heavily affected by the yellow channel? Nikon D700, AFS 60/2.8 G Micro

Although highly saturated color is visually striking, and B&W images are timelessly classic and elegant, there are a lot of times when neither is appropriate or an accurate representation of the scene. I’ve recently realized that I like accurate color above everything else – saturation control then becomes a matter of seasoning to taste. Color accuracy is actually quite critical when it comes to things like food – if the color of cheese or lettuce is off, it just looks moldy or unfresh. This is definitely NOT good for commercial work! My recent work is what I’d call in a ‘natural’ style – the color, saturation and hues are as close to my perception and remembrance of the scene as possible. I’ll do some shifting of white balance to make things warmer or cooler as required, but not a huge amount because it can do some very strange things to tonal accuracy.

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Scarlet Ibis. The red in is plumage is due to pigments in the shellfish that forms the majority of its diet. Leica V-Lux 3

Skin tones are perhaps the most difficult to replicate accurately; this is because skin is both reflective of ambient light (easy for the camera to capture) and emissive – we’re warm, and there’s some passive IR radiated by warm objects. Although modern cameras have very effective UV/IR blocking filter packs, they also produce (in my opinion) slightly dead-looking skin tones. I actually liked the skin tones from the Leica M8 for this reason, which was notorious for having perhaps the weakest UVIR filtration of any camera on the market – to the point that to get accurate blacks you’d have to use a UVIR filter on your lens.

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Black fabrics in the sun are notorious IR-emitters. Leica M9-P, 28/2.8 ASPH

Other objects that are notoriously difficult to reproduce accurately are flowers, some animals, and some fabrics. Again – this is because of the way they interact with the near-UV and near-IR spectra, which affects the way our eyes perceive color (though we can’t see UV or IR directly unlike some animals). To date, there is no camera that accurately reflects the spectral response of the human eye – and I suspect it might be very difficult to make one, because the filter pack would have to be calibrated to transmit or cut out a certain amount of each wavelength. It’s much easier to make a filter that cuts out everything above and/or below a certain wavelength. Throw in the added complication of mixed light sources, and you’ve got a minor nightmare.

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Colors. All of them. Which one do you balance for without shifting the others? Answer: focus on your subject – in this case, skin tones and blacks. Olympus E-PM1 Pen Mini, 45/1.8

So what can we do to achieve perfect color?

First clarification: we are not trying to achieve perfect spectral reproduction; we’re trying to achieve perfect perceptual reproduction. It’s not quite the same thing. Basically, you want to get to the starting point of being as close to what you remember seeing as possible, then work from there. That way, you know that all of your tweaking isn’t going to create some strange shifts in certain parts of the tonal spectrum.

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Chilis. Nikon D700, AFS 60/2.8 G Micro

White balance is inextricably linked to color. And there are some important things one has to bear in mind:

1. You have to get it right first time if you’re shooting JPEG. There just isn’t the tonal headroom in 8 bits to be able to make anything other than minor channel adjustments and not encounter posterization or weird hue shifts.

2. Manual white balance and a piece of paper are your best friends.

3. If you’re shooting RAW, white balance is less critical, but if you blow a channel, you’re not getting it back. Usually reds and yellows are the first to go. With earlier cameras, you might have to underexpose by as much as two stops to maintain tonal detail in the reds. I think it’s something to do with IR-sensitivity, the effectiveness of the filter pack over the top of the sensor, and how the red pixels respond very strongly to IR pollution.

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Cigars are one of the most difficult colors to get right. I don’t know what it is about the tobacco leaf, but that rich, deep brown hue requires a lot of work to perfect. Nikon D700, AFS 60/2.8 G Micro

4. White balance does affect exposure. This isn’t immediately intuitive; the reason is because if you get it very, very wrong, you’ll find that after correction, the dominant colors in the shot will shift, and the sensor may not have gained up enough at the extreme ends (red or blue) resulting in underexposure – most likely. You can to some extent recover this in post, but the bigger problem is that you’re going to land up with a very noisy image – the blue channel is generally holds the most noise for most cameras as it is the least sensitive due to the laws of optics, photon energy and filtration…but I won’t go into that here; complex quantum mechanical formulae are beyond the ability of my blogging software to input and display. ūüôā

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Prayer wheels, Nepal. Nikon D700, 24/1.4 G

Bottom line: shoot raw, and get in the right ballpark. Small adjustment are fine, and you can never get it 100% right all the time with a manual balance because ambient light is always changing. AWB works reasonably well on most cameras these days, but you have to watch out for the very warm light sources. I was told by several people in the camera industry that it was a conscious choice to leave the yellow/red components in the tungsten AWB because people expect the light to be warm (back to perception) – and having pure whites just looked odd to most consumers. I can attest to that as a lot of my students have asked me why the color is so blue when shooting indoors! Although I can’t say whether it’s a visual expectation on the part off the photographer, or whether inaccurate white balance is something they’ve come to expect because it was inadvertently dictated by the industry.

I’ve been playing with a handy little tool recently called a WhiBal. Basically, it’s a very, very accurate neutral gray card. I’ve found there are two ways to use it – one, take a shot under AWB with the card in the frame, and use that as your reference frame; eyedropper tool WB from the card in ACR, then sync white balance between the remainder of your files. Note that these two methods only work when your lighting is consistent from frame to frame, i.e. under studio conditions. The other option is shoot the card under the lighting conditions you’re going to use to set the preset in camera; I find this works better because all of your frames are automatically synced from the shoot. And if you’re using the same setup – as I do for watches – I can basically do it once and just leave one of my manual presets to match my flash and diffuser combo.

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If any of you have shot purple flowers, you’ll know they’re notorious for shifting towards blue: that’s because of the UV reflectance. Flowers have UV and IR reflective pigments to signal to other animals – in this case pollinating insects and birds – that can see UV and IR.
Nepal. Nikon D700, 24/1.4 G

Next, make the tweaks – in your RAW converter, (I use ACR 6) perfect your white balance. Use the eyedropper tool on various gray areas in the scene until, it looks close to what you remember. (This is another reason why I like to process as close to immediately as possible: you might forget what the originals scene looked like, or any processing ideas you might have had at the time). Don’t worry if the eyedropper tool doesn’t get it right; you can shift the color temperature and hue sliders a little until you do.

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This blue is one of the most difficult colors to get right. What makes it so appealing as a car color – the fact that it changes a lot under different lighting conditions – also makes it a royal pain to photograph and represent accurately. The honest truth is that I have no idea what RGB value this actually is, because it’s both reflective and in many spectra. Nikon D700, 28-300VR.

Open your file, make whatever contrast adjustments you need to – curves/ levels – then only use the Hue/Saturation tool to adjust the individual channels. Using curves inevitably shifts the saturation and hue slightly – there’s no way out of that – so you’ll need to bring back the individual channels. For instance, if it’s predominantly red and you used a curve that darkened the image, you’ll have to compensate for that by reducing saturation and increasing lightness slightly in the Hue/Saturation tool. There is no exact science to this – it’s all about experience, perception, and having the most accurate monitor you can find.

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Remember what I was saying before about shellfish and birds? Nikon D700, AFS 60/2.8 G Micro

Each camera has a different filter pack and spectral response. Even though manufacturers try to keep the color output consistent from model to model, there will be differences. The D3100, for instance, has a crappy color gamut that I was never happy with – much like the NEX-5 – however, the D700, D5100 and D7000 are all pretty similar. The D800 is close, but even more accurate and with a wider supported tonal range out of the box. The M8 with UVIR filter, M9 without and S2 are almost identical. Since I use a whole bunch of cameras – at the last check, Leica, Nikon, Olympus and Ricoh – I’ve created individual color profiles for each camera in ACR and saved them as camera defaults. The look I like is somewhere between the tonal richness of Leica and the warmth of Olympus – perhaps Olympus + Zeiss glass describes it best. Oh, and different lenses have different spectral transmission characteristics too, just to make life more interesting. Your personal preferences will almost certainly be different because each individual perceives color differently. But I suggest that if you have the time, this is a worthwhile exercise.

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The challenging pale but saturated lightness of macaroons. Nikon D700, Carl Zeiss ZF.2 2/2.8 Distagon

One important final note: all of this is in vain if your final output use is extremely limited gamut or highly compressed (*cough*FACEBOOK*cough*) – all of the additional tonal information you tried to save is going to be lost and compressed to hell. Some browsers (Safari) and photo sharing sites (Flickr) are better than others because they are color profile aware and don’t compress images, but the issue then becomes monitor accuracy. So unless you know the final output method and have some control over it, it’s very tricky to ensure that everybody is seeing the same thing. And printing is a whole separate blog on its own…MT

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POTD: Primary colors

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Primary colors. Nikon D700, 28-300VR.

Here’s a good example of an image that wouldn’t work at all in black and white…to be the subject of an upcoming article! MT

The inexact science of color and emotion

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What makes this photo identifiable as dawn instead of sunset? Hint: it’s the color. We expect sunsets to be warm, but mornings to be cool and clear.

A series of experiments was done many years ago that showed humans have been conditioned to expect certain things in the way of color: blue ketchup just doesn’t fly, for instance. The theory is that it’s a primeval subconscious response to warn us of danger. Think of it this way: rancid meat looks a certain way, and has a certain color. Even if we can’t smell it – looking at a photograph of vomit or something decomposing makes us go ewwww. Such examples are to be found in nature all the time – think of those brightly colored poisonous beetles, for instance. In fact, the link between color and range (and thus emotion) is so strong that many species mimic the coloring of more dangerous species to warn away predators, but at the same time rely solely on that as protection because they pack no venom or toxicity. (Toxicity is energy-consuming to produce, and in food-scarce environments, you want to waste as little of your nutritional intake as possible producing something that’s only going to help you if you’re eaten – and thus probably going to die anyway.)

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A tale of two cities. Shot minutes apart, though. How does the first image make you feel? The second?

How does this relate to photography? Quite simply, when you look at a photograph, how does it make you feel? Ignore the subject for a moment. The remaining emotional response is mostly down to your reaction to the processing: specifically, color. Why do black and white images have that ‘timeless’ or ‘ageless’ quality? Why do they make you feel slightly detached, as you’re an observer but not really part of the scene? It’s all due to color, or in this case, the lack of it. It’s difficult to relate to something if your information or perception on it is limited to tonal information only.

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Why does this shot imply richness and juiciness? How would you feel about pale gray steak with red tomatoes, even if it tasted the same?

In fact, if you look through historical photographs and video – you’ll see that each recent era or block of ~10 years in modern history actually has quite distinct color and tonal styles. And looking at this often makes one feel something – nostalgia, hatred, wondering what one was doing with their youth. Early color photos from the 1930s and 40s have that vintage look, for instance.

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To me, this screams classical photojournalism – because of the contrast, the tonality, and the lack of color. Early photographers didn’t purposely go for that look – they learned to work with it because of the limitations of darkroom chemistry.

A lot of modern photography software capitalizes on this. Instagram and all of those software filter packages are a good example – hell, even Lomography to some extent – they let you instantly create a feeling through a combination of color fiddling and contrast manipulation. There’s a reason why a photo from a Lomo or Instagram looks like a vintage hippy polaroid: it’s because the white balance was shifted warmer by several notches, the saturation decreased slightly, the contrast decreased a lot, and the relative luminance and hue of the red and yellow channels shifted. And there’s probably some grain and gaussian blur in the mix, too. Try it yourself in Photoshop, if you don’t believe me.

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Cool mountain. Nikon D700, Zeiss ZF.2 2/100 Makro-Planar

The point is, polaroids looked that way because of the chemical process of the day: not because they wanted them to look that way. I’m pretty sure the engineers there were chasing perfect color, too. The upshot of all of this is that a modern photograph processed that way invokes memories of the polaroid era, because that’s how most social images looked then.

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Mmm, natural green freshness.

Most humans respond in similar ways to color, namely:
Red – danger, warning, attention;
Blue – cool, calming, relaxing;
Yellow – warm, friendly, open;
Green – natural, fresh;
Black – mysterious, sinister, classic, premium, heavy;
White – pure, open, light, honest, clean
Gray – apathy

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Multiple light sources can be confusing as hell, but almost always signal ‘party!’

Simply put, there’s a reason why most Ferraris are red, and most hospitals are white.

How does this help you as a photographer?

Actually, it’s fairly simple. Color enters your image everywhere, but makes an impact in at least two major ways. The first is if you’ve got one dominant color in the scene that registers on the subconscious of the viewer even before they figure out what the subject is; it can be the color of the backdrop, for instance. A more subtle way is the ambient light temperature – for instance, a warmer white balance setting will result in a shift towards the red and yellow channels; this in turn imparts the ambient light with a particular quality and tone.

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Warmth. The ambient WB was shifted further away from the primary light source (the flame) to preserve the warm color.

The second major way is through contrast: if you’ve got a subject of one color against a backdrop of another completely opposite color (red and green or blue and yellow, for instance) then it’ll stand out because it’s the only thing in the scene that is visually discordant. It’s a good thing, in this case, because it draws your eye to the subject and lets the background serve as a stage – which is the way it should be.

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Why does my subject stand out? It’s a different color to the background, of course.

But what if your scene has no dominant color, or is very washed out or low in saturation? Do what the cinematographers have been doing for years, and either impart a global tint as described above – you can easily do this if you shoot raw by shifting the white balance; lower color temperatures that what is accurate are cooler and bluer, and vice versa for higher color temperatures. The other alternative is to use a filter over your lens, or color the light – the latter obviously assumes you’ve got some control over your lighting, though. By far the easiest way to shift color and not land up with odd hues due to the nature of color addition and subtraction is to adjust your white balance.

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KLCC dawn, color slightly shifted. Nikon D700, 28-300VR

One final comment: you need to start with an accurate white balance before you shift the color temperature. This is so you don’t land up with strange colors due to shifts along the green to magenta axis (white balance and color temperature affects only blue to orange/red). Also, remember not to overdo the saturation: shifting the white balance can cause other channels to blow, even if the original appeared to be correctly exposed. And over saturated images just look crude, frankly.

And on that note, I’m going to break until the next topic: chasing perfect color, and white balance myths. MT

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Funky diner colors. Sometimes, your ambient light is close to exactly what you want – and all you have to worry about is color accuracy. Nikon D700, 85/1.4 G

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Visit our Teaching Store to up your photographic game Рincluding Photoshop Workflow DVDs and customized Email School of Photography; or go mobile with the Photography Compendium for iPad. You can also get your gear from B&H and Amazon. Prices are the same as normal, however a small portion of your purchase value is referred back to me. Thanks!

Don’t forget to like us on Facebook and join the reader Flickr group!

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Images and content copyright Ming Thein | mingthein.com 2012 onwards. All rights reserved