| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that the number of samples constituting the feature value space of an observation picture is not sufficient in a region where the density of the picture is low and therefore the detection precision of access control information remarkably drops. SOLUTION: The Mahalanobis distance MD1 between the feature value space (the set of feature value vectors) of a reference picture and a reference vector is calculated (S1). M×N pixel blocks are cut from a picture signal as the observation picture (S3 to S7). The number of samples which can be used for constituting the feature value space of the observation picture is compared with a prescribed value (S10). When the number of samples < the prescribed value is realized, the area of the observation picture is extended to a plurality of blocks (S12). The Mahalanobis distance MD2 between the feature value space of the observation picture and the reference vector is calculated (S14). The feature value space of the observation picture is moved so that the relation of MD1 and MD2 is controlled in accordance with an access control signal (S15 to S17). Then, the observation picture is reconstituted based on feature value space after movement (S18).
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