| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the loss of information on a number plate caused by luminance conversion by setting the range to guarantee the settlement of gradation levels of an object to be identified from lower slice to upper slice and intensifying the gradations within that range. SOLUTION: Concerning the area portion of minimum black part of the number plate, a lower slice 10 is determined by lower slice calculating processing 9 so as to cut it from the downside. Concerning the area portion of minimum white part of the number plate, an upper slice 12 is determined by upper slice calculating processing 11 so as to cut it from the upside. Thus, the range is widened by contrast intensifying processing 13 so that the luminance of portions from the lower slice 10 to the upper slice 12 can become a saturation level from the lower limit of luminance, and contrast is intensified as the gradation within that range. Thus, the minimum contrast of the number plate part can be guaranteed. |
