| 摘要 |
PURPOSE:To eliminate the influence of the brightness/darkness of the entire screen by detecting an edge by means of a change in a multilevel data, and detecting a plate by using the number of pieces of detection data. CONSTITUTION:The image of a vehicle is picked up by an image pickup device 1 whose output is A/D-converted by an A/D converter 2, and the data is stored in an image memory 3 as a multilevel data: eight bit per one picture element in 256 gradations. The multilevel data is transmitted to an edge detection triplevalue-processing part 4, where it is subjected to the triplevalue-processing for edge detection, thereafter stored in a triplevalue memory 5. A triplevalue code vertical counting processing part 6 counts the number of pieces of triplevalue code in the vertical direction of a screen, and the result of this counting is transmitted to a plate detection processing part 7. The plate is detected by the part 7, and respective characters are recognized by a character recognition part 8 and a normalization processing part 9.
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