| 摘要 |
PROBLEM TO BE SOLVED: To properly make average noise amplitude of an image signal uniform according an image pickup condition of the image signal by preparing gradation conversion by every image pickup condition to be a fluctuation factor of dependence relation and deciding proper gradation conversion according to the image pickup condition of the image signal. SOLUTION: The image signal of an imaging device 13 is amplified to a signal gain corresponding to setting of image pickup sensitivity via a variable gain amplifier 14, linearly quantized by an A/D converting part 16 and defined as a digital image signal equivalent to 12 bit of each color. On the other hand, image pickup sensitivity setting information is acquired from a noise estimating part 18 and an image sensitivity setting part 15, a conversion table is selected from an internal storage area by the information, data are transmitted to a gradation conversion calculating part 17 and the gradation of a digital image signal outputted by the A/D converting part 16 is converted by using the data. Thus, since the proper gradation conversion for the image signal is selected according to setting of sensitivity in the case of image pickup, average noise amplitude of the image signal is exactly made to be uniform even when the setting of the image pickup sensitivity is changed.
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