Why does my subject's skin have such a red cast — did my auto white balance fail me?

Question

I have close to two hundred images where the subject looks like he just walked out of a sauna. It was 36 degrees with humidex, but he was not that red.

For comparison, attaching another picture, same camera, same lens, auto white balance, next day.

So, two questions, 1) how did that happen?, and 2) how do I fix it? I can bring down the red, but then I have to manually bring back the lip color in 200 pictures.

And next time when I deal with an older guy at 36 degrees C I will be shooting indoors.

*Edit: The camera is Olympus EPM 2. I am now guessing that he may have been THAT red, but my eyes tricked me. The last picture is from the beginning of the shoot before he got very hot and had two glasses of wine AND the background worked better for his skin and clothes. I do not have colour management setup, but I will get on it.

Answer 1

The problem with auto-white balance here is that you have in essence different scene elements. The brightly background is in the sun, the face is in the shadow. The lighting of the face is reflective, from whatever reflective light happens to be behind you.

Now if you look closely at the sun-lit areas in the background, they are brightly lit and should display sort of a bluish tint. But their bluish has a tendency towards magenta. This may be since the camera overguesses the bluish character of the composition by basically not being able to distinguish a blue shirt in the shadows from a midnight one. So it picks an average that turns out sort of unlucky.

A picture composition of that half-light half-shadow kind is hard for automatic white balance (it can actually be rather effective in black&white photography). You can simplify the job by cheating with the light, like using a weak flash (which would also serve to tame the background brightness a bit for the sake of the overall picture composition). For avoiding additional shadows, you can use indirection from the ceiling. A lightbox will also diffuse a bit: it's probably worth spending a few hours in different environments for figuring out how to best cheat your ways around "atmospheric" shots without spoiling them and developing your personal toolbox for those situations: when such tricks apply, they are usually good for a whole series of shots in one location.

You can, of course, fix up curves in post-production, but it's always worth working on getting the best starting material for that.

Answer 2

Based on the sample images you've provided, AWB appears to be working fine. Neutral objects appear neutral: The plate, the concrete wall, the gravel path, the door, the gray shirt.

You are likely not getting the colors you want because of the color profile on your camera or raw processing software does not match your preferences.  Camera and lens selection may also play a role.

Lens Selection

Lenses may transmit different frequencies differently. For instance, some produce warmer colors, while others are cooler. Some lenses also have defects, such as "glow", when shot wide open. Some people find that a soft-focus look is pleasant in portraits.

Auto white balance in some cameras normalizes color differences between lenses. In other cameras, it does not. Setting custom white balance typically neutralizes many lens color differences.

Camera Settings

If you are disciplined, you should set custom white balance. However, if you shoot in conditions with varied lighting, forgetting to change white balance can result in dozens of subsequent shots being ruined or wasting your time in post processing. (How significant this is depends on your workflow.)

Some cameras allow color-shift adjustments to auto white balance. Since AWB on my camera tends to produce images with more magenta than I'd like, I adjust AWB to increase the complementary color, green.

You should also select the color profile on your camera that best matches your preferences. Usually one or two profiles will subdue magenta-red colors. Available options vary by camera maker:

• FujiFilm: Provia, Velvia, Astia, Classic Chrome, ProNeg-High, ProNeg-Low.
• Canon: Standard, Portrait, Landscape, Neutral, Faithful.
• Nikon: Standard, Neutral, Vivid, Portrait, Landscape, Flat.
• Olympus (Picture Modes): i-Enhance, Vivid, Natural, Muted, Portrait.

• Sony (Creative Style): Standard, Vivid, Neutral, Clear, Deep, Light, Portrait, Landscape, Sunset, Night Scene, Autumn leaves.

• _{(Feel free to suggest edits with camera makers and profile names...)}

Cameras also typically allow adjustments to saturation, contrast, highlight, shadows, noise reduction, and sharpness.

Post Processing

The objectionable skin tones are most likely magenta, less so red. Even if the colors are accurate, you may still prefer less magenta.

Many tools do the same thing. The concepts underlying curves and levels apply to nearly every other color adjustment tool. Aside from that, use whatever tool is available or that you like best. Regardless of what you choose, it's helpful to know which primary and complementary colors go together (Red-Cyan, Green-Magenta, Blue-Yellow), as well as distinguish Red-Magenta and Blue-Cyan.

• You can reduce the magenta by adjusting curves to increase the complementary color, green, in relevant areas. Use color-layer blending to avoid changing the overall luminosity of the image. Use layer masks to isolate changes.

• You can do the same thing by adjusting levels. You can use the "auto" button or select white, gray, and black points with the dropper tool. Then look at each channel to see what the software did to use as a starting point for your own adjustments.

• Sometimes desaturating slightly is enough to fix skin tones. Use a layer mask to isolate changes.

• Some people like HSL/HSV/HSB adjustments. I don't use them at all because I don't know how to adjust "Hue" to get intended results consistently.

• You can also try adjusting temperature and tint. (These, along with saturation, are the main color adjustment tools available in Google Photos.)

• Some editors include skin-tone specific tools. If these are available to you, experiment with them until you find settings you like.

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Here is the result after adjusting the magenta-green curve, masking to limit the effect to the face, desaturating slightly, and applying a contrast mask:

Answer 3

To make it simple the Auto-WB more or less tries to make a grey picture. In the second picture, the WB likely compensates for the red brick wall, and so reduces the red (the door on the right is also a near perfect neutral gray...) . In the first picture, the blue shirt could have the opposite effect, even though, like others, I don't find the picture unnatural (check the arms and hands).

Answer 4

Some brightness and contrast curve increase, desaturation and color temperature adjustment goes a long way for compensating for what amounts to a shadow shot with a sunny background. The brightness increase actually deemphasizes the background by levelling it out more, and there is not much of a point of trying different adjustments for fore- and background since making the background more detailed/consistent is mostly a distraction. Of course there actually is a slight reddish flush to the face but on the original shot it almost is part of a uniformly magentaish haze on the face essentially coming about by its placement in the shadow against greenish background and also affecting the tint of the hair.

The camera may contribute some of the oversaturation in the shadow due to its white balance choices, but the scene composition as such is not unproblematic without external lighting correction.