| 摘要 |
A film retrieval system comprises a light source for illuminating a film having marks applied thereon, a photo-detector for detecting light intensity transmitted from the illuminated film, a device for determining a reference in accordance with the light intensity detected by the photo-detector, a discriminator for determining the presence or absence of the mark by comparing the reference determined by the reference device and an output of the photo-detector and, a setting device for setting a detection point of the transmitted light intensity by the photo-detector at any point spaced from a leading edge of the film.
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