What is "Good" Skin Tone?
This is the photo that caused me to return a camera. Which is kind of crazy because I really do like this photo a lot.
I've spent a lot of time thinking about photographing skin tone - what is good or bad skin tone? And most importantly of all - does shooting RAW mean you can always get good skin tone?
Evolution
We evolved to see green first. Green actually covers a pretty broad spectrum, but most importantly it's the color of foliage - of plants we can eat.
We then evolved to see red. The red spectrum overlaps with green considerably, which means we're very attuned to seeing subtle differences in this range. The benefit of this is that we can now see fruits and predators against the foliage.
Most importantly for our discussion - we evolved to see subtle differences in skin tones. What fruits or meats were good to eat or not, what people were healthy or not. Millions of years of evolution made us very sensitive to "good" or "bad" skin tone - whether we're consciously aware of it or not.
Above: Notice how skin tone is an interplay of green + red to make yellow.
Finally we evolved to see blue. Blue is further away from red and green, and we have the least sensitivity to it, meaning we're less capable of discerning subtle differences in blues.
Above: Notice how good skin tone is an interplay of yellow + blue and how quickly it can become too yellow, too red, too magenta. Also notice how the green sections seem the most solid, we still perceive it as the most important color.
The addition of blue also gave us the strange color magenta - which is the absence of green, it triggers the red and blue receptors on opposite sides of our frequency spectrum. This is why magenta is so rare in nature.
Human skin tone is a very delicate balance of these three colors - get it right and someone looks healthy. Get it wrong and - disaster.
What is Bad Skin Tone?
Before we get to good skin tone, let's take a look at bad skin tone. I've stumbled on a few cameras that I think give consistently bad skin tone and found some examples on Flickr.
Bad skin tone manages to be too yellow and too magenta/red at the same time. If you look closely at your own skin - your palm or the inside of your wrist are often good examples. Your skin will likely have bits where it's thinner or thicker - veins and capillaries closer to the surface or not. This creates a subtle variation in hue. Looking at my own hands in good (indoor daylight) light, I can see there's a leathery spot that comes from using a computer mouse all day long and very blue veins next to fairly red arteries in my wrists.
Not everyone will have this much variation (nor this transparent skin) but getting this balance right is important no matter what your skin tone.
We all have these subtle variations in skin tone, but some cameras exaggerate it more than others. What makes this difficult to work with is that red and yellow are adjacent on the color wheel, and magenta is almost but not quite opposite yellow.
When I start to complain about this, usually someone chimes in with a very helpful "You get good skin tone by shooting RAW and with post processing skills." Translation: the equipment is never to blame, it's all your fault.
I hate this argument. It's neither helpful nor informative. It just places blame without offering a solution.
So let's try to fix this skin tone. I just have the JPGs of these files, but I can still open them up in Photoshop and do the usual editing moves.
First let's try to reduce the reds with curves. Well that's a little better.
Though red is opposite cyan so by reducing red I've introduced cyan and he's looking a little sickly. Maybe I should have reduced the saturation of the red channel instead. You can see how this gets complicated & these decisions require knowledge and skill.
Mind you, this is a particularly strong example and this gentleman's skin may well be "either red or yellow" with little in between. My contention is that some cameras emphasize this more than others.
This is the kind of thing that would drive me mad - it's impossible to get rid of one color without emphasizing another. Getting rid of yellow introduces blue, which makes the reds more magenta. It's all connected.
If only there were a tool that could just sort of suck the colors from different points on the color wheel and bring them together, reducing the variation in hue.
I always assumed that I could reduce the variation in color if I decided to work in LAB color mode, but could never quite figure out what to do to achieve the results I wanted.
Enter Capture One. It was tremendously validating to me when I found out that Capture One had a Skin Tone tool that did exactly this - increase uniformity in Hue, Saturation and Lightness around a selected range. This edit took maybe 30 seconds - another 30 seconds and it would be dialed in even better. (I went a bit too far in making things uniform and I would want to further tweak the hue. I just wanted to show the power of this tool to quickly resolve the "too yellow or too red" issue.)
Finding this tool I realized I was right - "good" skin tone is reducing variation around a central "good skin tone" range.
And of course this is all very subjective - "good" skin tone is a subjective term after all. All color is subjective - it only exists inside our minds.
RAW is RAW
This is my argument against "if you shoot raw and have post processing skills, you can get good skin tones with any camera."
Before discovering the Capture One tool, my method for this would have been to create a Curves layer in photoshop, correct for both the "too yellow" and the "too red" on different layers, and then painted in on each section as needed to reduce the variance between the two.
This is a technique I learned from a Lee Varis tutorial who - as far as I can tell has some skill in post processing.
While the results were good, it was sort of tedious and annoying and not something I could do in batch.
Because "good skin tone" as I'm defining it is such a narrow target "neither too red nor too yellow" it's very easy to overshoot it - not only that but you can't pull it in one direction without pushing it in the other.
I contend that some sensors are overly sensitive to this. The color filter array that allows them to detect color is itself tuned to be sensitive or not to specific frequencies & if they don't overlap in just the right way - it exaggerates what should be a subtle difference in color.
I've never shot Leica, but my impressions of Leica are that this is the case.
The following photographs are images I've come across from Leica cameras that display this tendency.
This is a very heavily edited photo taken with a Leica M 240. To the point where you may wonder whether or not the red/magenta vs yellow issue is a purposeful effect
What about this, presumably unedited photo of a popular youtube camera reviewer taken with the Leica SL2.
Or this, more subtle image from another popular youtube camera reviewer. At first glance, this image looks fine.
But what is all the more interesting about this is that it's a video, so you can track the same patch of skin across time.
A small change in luminosity leads to a large shift in hue* and it unfolds in real time in front of your eyes.
* no pun intended
So if you're shooting RAW and you import a file whose colors are simultaneously too red/magenta and too yellow - how do you edit them?
My contention is that "RAW is RAW" is a fallacy because while they do offer a lot of latitude in how they're processed, it's possible to overshoot the mark and it takes a delicate hand to dial it back.
Most people think the RAW file and RAW conversion process are equal - each having a 50% impact on the final result.
I agree that they're equal, but 50/50 would be additive, and it's not, it's multiplicative.
It's not 50/50, it's 10/10.
10% x 10% = 100%.
This means that any tiny difference in the RAW file is multiplied by any tiny difference in the RAW conversion process. Which means that if both are 1% off (9.9% x 9.9%) the end result is 2% off (9.9 * 9.9 = 98).
And when editing skin tone, 2% off is a lot.
Which brings us back to the photo that made me return a camera. I like to think I have some skill when it comes to editing photos. If a camera RAW file and the way Adobe treats it doesn't get me to within 2% of what I want, I can only envision a future of me fighting with that camera to get the colors I want.
Was I irrational in returning it? Maybe. Could I have tamed it? Maybe, but I had a limited window to return it and I made my decision.
What Photography can learn from Videography.
In video editing, they have something called a "skin tone line" - a line on the Hue/Saturation vector-scope that represents "good" skin tone. This gets you to a ballpark region where most people's skin tones will look good, regardless of ethnicity. You can think of it as white balance for skin tones.
Then there's the amount of saturation - darker skin tones tend to be more saturated, which means they're also more sensitive to slight variations in hue overall - if the camera gets the skin tone a little bit wrong on a pale person, they'll get it a lot wrong on a person of darker skin tone. Though subtle variations in hue tend to get exaggerated more with lighter skin tones.
Modern cameras tend to go for a more "punchy" saturated look, which can exaggerate subtle differences in color processing for darker skin tones. Take a look at the difference between "Standard" (left) and "Portrait" (center) color modes on this camera. To the right is the X-Rite Color Checker calibrated RAW version
In each row there are differences between each image, but the more pigmented the skin, the greater the difference from image to image. All images have the same white balance.
In no case would the X-Rite version have been my preferred starting point - it's too green.
Check out this video to learn more about the "skin tone line" and how videographers use it to get "good" skin tones regardless of the camera used or the lighting situation.
Final Thoughts.
This post won't put to rest the "RAW is RAW" argument, nor the "getting good skin tone is a matter of skill in post processing" argument.
What I hope is that it introduces the idea that subtle variations in our real skin tones can be exaggerated by the imaging pipeline. That some cameras are overly sensitive to this and exaggerate that difference. That regardless of skill, some some things are difficult to fix in post.
PS - the RAW files from some of the Leica SL2 images are available to download on the DP Review website, so you can use them to debunk me all you want. :)
Credits
Model for first image.
https://www.instagram.com/milabogofficial/
Open License Images
https://www.flickr.com/photos/jaap_spiering/35280792671/
https://www.flickr.com/photos/rossap/8553766697/
Copyright Reserved Images
https://www.flickr.com/photos/32681588@N03/26665342303/
https://www.youtube.com/watch?v=yilmHb7gx10
https://www.youtube.com/watch?v=ajCU94KAUzU
These images are used under fair use.
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