RENEE MONTAGNE, host:
One of the mysteries of great painting is how artists use color. Some artists paint realistic colors that match nature. Others elicit emotion with lurid, unnatural colors. Color is the artist's wild card, but color fades, and that can ruin what the artist is trying to accomplish. NPR has been examining how art and science intersect. In this story, NPR's Christopher Joyce reports on a scientist at the Rochester Institute of Technology who's using science to rescue great art.
CHRISTOPHER JOYCE reporting:
If art is something that transports you away from where you are, then let's imagine strolling alongside the River Seine in Paris.
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JOYCE: White sails, shimmering water, statuesque women in Sunday dresses, men recline on the sunburned grass while pet dogs nibble at a spilled picnic lunch. This scene is "Sunday at la Grande Jatte," painted by George Seurat. In the late 19th century, the painting was a scientific breakthrough. By painting with tiny dots, Seurat created luminosity; his figures glowed. This new art, like this music, was unmistakably French.
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JOYCE: But over a century, the painting's yellows turned as brown as an August wheat field. Then a scientist, the man playing this very French music, figured out how to fix it.
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JOYCE: When Roy Berns isn't playing his guitar, he's a scientist.
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Mr. ROY BERNS (Scientist, University of Rochester in New York): We're in the spectral color reproduction lab.
JOYCE: Black walls, black cabinets and broad display tables, this is where Berns figured out how to bring Seurat's "la Grande Jatte" back to life.
Mr. BERNS: Here's a print of the detail. We can see it better on the display.
JOYCE: Up close, you can see the points of paint that Seurat carefully laid down on the original canvas. Seurat mixed in a zinc yellow to make different hues, for grass and trees, for example. When the yellow turned brown, more than color was lost.
Mr. BERNS: It certainly changed what he was trying to achieve, which was to create this notion of luminosity.
JOYCE: The Art Institute of Chicago, which owns "la Grande Jatte," analyzed the paint chemistry and determined what the original yellow paint would have looked like. Then they asked, could you re-create that yellow in a print that would look just like the original did the day it was painted? It was a daunting task. Berns went over the canvas with a spectral photometer. This handheld device measures the different wavelengths or types of light reflected from a surface. By taking scores of measurements, he got a sort of spectral fingerprint of the whole painting. Then, as he likes to say, he did some math and used a computer to make a copy.
Mr. BERNS: I ended up calling this work digital rejuvenation. So we wouldn't be changing the actual painting, but if we could change this digitally, then I can make a print to demonstrate this.
JOYCE: The museum showed Berns' print along with the original. The difference was striking. For example, Berns' unaged version showed how Seurat employed simultaneous contrast. In this technique, you surround a figure with a complementary color or, in Seurat's painting, a lighter hue.
Mr. BERNS: This is part of how our eyes' physiology works. And you can see that these sort of complementary halos around some of the figures are much more prominent. So there's this woman sitting in the foreground, and she has this lightened halo around her in order to accentuate the form.
JOYCE: Several museums are now using digital rejuvenation to make true images of old masters that have deteriorated. Applying science to art brings Berns full circle. He painted as a child but chose science as a career that led to various places: dyeing carpets for casinos in Nevada and to a courtroom as a witness in a lawsuit involving Procter & Gamble. The company claimed its toothpaste made teeth five times whiter than its competitor. Berns proved it actually did.
Now he's trying to correct some of the tricks that light plays with art. Here's an example: Let's say you paint something outdoors under natural light. The colors may look just right, until you bring the painting indoors under artificial light or print the painting in a book. The colors shift. It's a process called metamerism. To illustrate, Berns takes me to a sunny hillside in Rochester. It's the annual Lilac Festival and crowds are strolling among acres of pale-blue blossoms. To Berns, however, it's not simple blue.
Mr. BERNS: If you look at the flowers, we're seeing changes in lightness, changes in chroma, how much color, but also we see slight changes in hue going from purplish to bluish to reddish. And the only way you're going to get that range of hues is by having a combination of pigments.
JOYCE: Berns takes a handful of blossoms back to the lab and scans them with a spectra photometer. His computer does the math to convert their reflected wavelengths into a curve on the screen; you could say the lilac curve. Then Berns compares that with curves of various pigments, and two common ones seem very similar to the lilac; quinacridone violet and a mixture of ultramarine blue and naphthol red. Berns mixes real samples of both and puts them with the blossoms in a light booth. It creates different kinds of light.
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JOYCE: Under sunlight, the quinacridone violet looks like the best match. Same goes for late-afternoon light. But under indoor lighting, it's no longer blue. It's red.
Mr. BERNS: We can see that, in fact, this quinacridone violet is really a very bad match under gallery lighting. So here would be an example where, you know, your hard-fought-for color is going to be really bad in the gallery.
JOYCE: Berns is working with museums to design cameras and inks so they can produce more accurate copies of great artwork that won't change appearance under different light.
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JOYCE: At the Smithsonian Institution's Museum of American History in Washington, conservators are applying Berns' research to help restore an exhibit, Old Glory, also known as the Star-Spangled Banner. The flag flew over Ft. McHenry during the War of 1812. Now it's tattered and faded. Today it's spread out in a laboratory at the museum behind a glass wall where the public can watch as it's restored. Textile curator Suzanne Thomassen-Krauss says Berns helped them find a new backing for the flag, one that won't distort its true colors. Mounting is important, too. Viewed from the wrong angle, the colors won't be right. And, of course, the lighting is crucial.
Ms. SUZANNE THOMASSEN-KRAUSS (Textile Curator, Smithsonian Institution's Museum of American History): When you look at a lit object, what you're getting is only the light radiation that's reflecting back off the object. Everything else is doing damage, because it's actually being absorbed by the material. So what we want to do is fine-tune that special characteristic of the light so it shines back and it doesn't absorb into the material and cause damage.
JOYCE: That means low light, perhaps something like dawn's early light, but definitely not rockets' red glare. Roy Berns says what curators and conservators want is to banish the effects of age and the unintended quirks of light and color. That means sometimes going back in time, which he can do, he says, so long as he can figure out the math. Christopher Joyce, NPR News.
MONTAGNE: This is NPR News.
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