Why are flesh tones harder to print?

Answered by Stephen Beals, Digital Pre Press Manager and Writer

Why are flesh tones harder to print?

Flesh tones are considered difficult to reproduce for several reasons. Most of the reasons have everything to do with the way the human brain works: not the way the printing process works. First, we know what a "pleasing flesh tone" looks like. The human eye is more discerning of "memory colors" more easily than it it is of colors it cannot relate to immediately. The blue of a sky and the green of grass or the red of a barn in the country are known as "memory colors" because your brain instantly knows what those colors are "supposed" to look like. If the sky is too red or the grass is too blue, it tends to look "off" or "fake". Flesh tones are the same way.

The values of the ink printing in flesh tones are also mostly highlight values, at least for Caucasions. A few percent variance can make the face look "washed out", or pale. Too much yellow makes a person look jaundiced. Too much red makes them look flushed, and too much blue makes the face look waxen. The human eye is much more discerning of variance in highlight areas: it's simply the nature of the eye's optics. A ten percent difference in the three quarter tone area of an image is a lot harder to see than a 3-5% difference in a quarter tone.

There's one additional reason flesh tones can be problematic. And again, it's partly psychological. We are simply less tolerant of noise, flaws and screen interference (a natural part of any printing process) in facial areas than in other image components. Again, since these screening flaws are more apparent in highlight areas, that adds to our discomfort.

In truth, the hardest colors to match in the printing process are neutral grays. The tolerance for maintaining neutrality when multiple process inks are combined is very small. What is supposed to be neutral quickly ends up looking too "warm" (red or yellow) or too "cool" (blue).

But you are much more likely to have a job rejected if the flesh tones aren't right. It's just human nature.
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