초록 ▼

Elimination of dark fixed pattern noise (DFPN) for tethered CMOS sensor-based digital video cameras is supported by supplying and maintaining a host-based dark image cache. Since the camera is tethered to a host computer system such as a PC, it takes advantage of the storage and processing capabilit

Elimination of dark fixed pattern noise (DFPN) for tethered CMOS sensor-based digital video cameras is supported by supplying and maintaining a host-based dark image cache. Since the camera is tethered to a host computer system such as a PC, it takes advantage of the storage and processing capabilities of the host to manage the cache. By using a dark image cache for updating of the currently applicable dark image for DFPN cancellation processing, operation of the camera shutter for acquiring dark images is dramatically reduced, thereby using less system resources such as power, and increasing the MTBF of the electromechanical devices such as the camera shutter and associated controls. Dark images are obtained at different integration, gain, and temperature operating characteristics of the camera and stored in the cache. The cached dark images are referenced on the host according to a fixed, predetermined dark column of data in video frames generated by the CMOS sensor image array of the camera. The dark column data represents a portion of the CMOS sensor image array which is permanently and totally shadowed for use during DFPN cancellation processing.

대표청구항 ▼

[ What is claimed is:] [1.] A method of selecting dark images used in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising:providing a cache of dark images, the dark images being index

[ What is claimed is:] [1.] A method of selecting dark images used in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising:providing a cache of dark images, the dark images being indexed by a data structure, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor;obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames generated by the digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor;comparing the current dark image reference data obtained from the dark area of the current frame to at least one entry in the data structure of dark image reference data; andusing a dark image from the cache associated with an entry in the data structure of dark image reference data to perform dark fixed pattern noise cancellation processing on the stream of frames when the current dark image reference data corresponds to the entry.