In a camera system of CCD as sensor and utilizing CCD video signal integrated processor (video signal processor for short)
when gain is high
the black level auto-correction process of video signal processor will cause CCD image gray value vary slowly and sharply at the beginning stage with target brightness not varying. Based on XRD98L59 of EXAR
this paper analyzes the device structure and its black level auto-correction process
establishes the model of black level auto-correction process
determines the parameters by experiment
and verifies the correctness of the model. According to the calculating results of the model
the preparing time of the camera system is adjusted to 5 s
the problem that CCD image gray values vary "slowly" and "sharply" at the beginning stage is resolved.