Solarization
Solarization flips part of a photo's tones so it looks half positive, half negative. It began as a darkroom accident, and its name comes from shooting the sun.
What is solarization?
Solarization is an effect where some of a photo's tones reverse while others stay as they were, so the picture looks partly positive and partly negative. Shadows can turn pale, highlights can fall dark, and thin dark or light lines often trace the borders between them.
Today the word covers two darkroom effects and a digital filter. Strictly, it means film that got so much light it developed lighter instead of darker. What most people picture, the silvery Surrealist portraits of the 1930s, is the Sabattier effect, made by flashing a print or negative with light halfway through development.
Why is it called solarization?
The name comes from the sun. The effect was most likely first noticed in early landscapes that included the sun, which printed as a dark disc where the brightest spot should have been. The plate had been hit so hard that its response turned around. Ansel Adams made a deliberate example in 1939, Black Sun, Owens Valley, California.
You can see it on the characteristic curve Ferdinand Hurter and Vero Charles Driffield introduced in 1890 to describe how film responds to light. Density climbs with exposure, levels off at the shoulder, and with enough overexposure starts to fall again. That falling stretch is the solarization region.
The accident in Man Ray's darkroom
The Sabattier effect had been described in the 1860s, but it reached the art world by accident in Paris in 1929. Lee Miller, then working with Man Ray, wrote to her brother that something touched her leg in the darkroom, she screamed and switched on the light, and the film in the developer was exposed. The prints from it showed the strange part-reversed tones.
Man Ray made the technique his own and gave it the name people still use. Who discovered it is still argued, and Miller told the story more than one way, but the portraits they made turned a darkroom fault into a technique artists still copy.
How do you spot a solarized photo?
Look at the edges. A darkroom solarization usually has a thin outline, the Mackie line, where a dark area meets a light one. Tones in the middle of the range tend to go flat and metallic. A plain inverted negative has neither feature: every tone flips and nothing stays positive.
Digital solarize filters reproduce the tone flip with a curve that bends back down past a point. The 1960s poster artists liked the result in strong color, which is why the look keeps turning up next to psychedelic art.
Solarizing your own picture
Solarize Effect folds a picture's brightness at a Pivot. A side-lit portrait on a plain background gives the strongest outlines. Start on the Darkroom preset, then lower Colorize to 0 for a silver print look. For poster color, raise Colorize toward 0.8, which keeps strong hues in the parts of the picture that were bright to begin with.
