Abstract: A CMOS image sensor, a pixel unit and a control method thereof are provided. The pixel unit includes: a photoelectric conversion unit, an isolation transistor, a storage unit and a reading unit, wherein a first terminal of the isolation transistor is connected to the photoelectric conversion unit, a second terminal of the isolation transistor is connected to the storage unit and the reading unit; and wherein the storage unit comprises a first switch unit, a second switch unit, a first storage capacitor, a second storage capacitor and a reset unit, the first switch unit is adapted for controlling the first storage capacitor to be charged or discharged, the second switch unit is connected to the second storage capacitor and is adapted for controlling the second storage capacitor to be charged or discharged. The pixel unit improves signal-to-noise ratio of image signals generated by the pixel unit.

Abstract: An image sensor and an image processing system. The image sensor comprises: a CMOS photosensitive array used for converting an optical signal into an electrical signal; a control signal conversion circuit used for converting into a second control signal a first control signal for driving a CCD photosensitive array to operate, the first control signal at least comprising a vertical transfer signal, a horizontal transfer signal, an electronic shutter signal and a read-out clock signal, and the second control signal at least comprising a column address signal, a row reset control signal and a row read-out control signal; a row selection circuit used for generating a row reset signal according to the row reset control signal and generating a row read-out signal according to the row read-out control signal; and a column selection circuit used for conducting column gating on the CMOS photosensitive array under the control of the column address signal and outputting a column read-out signal.