| 摘要 |
In electronic film development, a film is scanned, using light, multiple times during development. The light is reflected from an emulsion containing milky undeveloped silver halide embedded with developing grains. The undeveloped halide layer has a finite depth over which photons from a light source scatter backward. This depth is within the range of the coherency length of infrared sources commonly used in electronic film development, causing coherency speckle noise in the scanned image. A prescan made after the emulsion swells, but before the silver grains develop, normalizes subsequent scans, pixel by pixel, to cancel coherency speckle and other defects.
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