| 摘要 |
PROBLEM TO BE SOLVED: To detect the reduction of a receiving light quantity caused by attachment of flaws and stains or deterioration due to aging of a light source. SOLUTION: A detection section 6 compares a difference image of a detection object with a standard difference image picked up before the difference image of the detection object, and detects the reduction of the receiving light quantity in the difference image of the detection object. Furthermore, in the detection section 6, a class difference is made to be the parameter of the reduction amount of the receiving light quantity; and when the class difference exceeds 3 classes for instance, it is considered that the reduction amount has exceeded an upper limit value and it is reported by a reporting section 7. Then, when a user notices reporting by the reporting section 7 and cleans a lens or a cover, exchanges a scratched lens or cover, or exchanges a light source with remarkable aging degradation with a new light source, the image quality decline of the difference image to be picked up, after the work is prevented. COPYRIGHT: (C)2011,JPO&INPIT
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