Texas Instruments Corporation

Xiaochuan Guo

Zhiliang Julian Chen

John Gregory Harris

Steven Derrick Clynes

Anli Liu

The pixels of an image sensor array can be readout ( ) in m&times;n blocks (m, n) that are compatible with the operation of a desired image compression algorithm ( ), thereby reducing the amount of memory required by the image compression algorithm.

Image sensor array readout for simplified image compression

This CMOS imager represents illuminance in the time domain. Once per frame, each pixel outputs a pulse after a time proportional to the illuminance on that pixel. Therefore, the illuminance on that pixel is related to the time difference between its pulse event and global reset of the imager. A counter reports the times of these pulse events in a digital format. Thus no analog to digital converter is necessary. This imager enables easy computation of pixel intensity histograms. Frame data is stored in pixel intensity order using row and column arbiters to produce a pixel address. Because each pixel has its own exposure time, the imager has a wide dynamic range of 120 dB. This imager has low power dissipation and avoids the noise and mismatch problems of prior complicated analog readout circuits.

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Xiaochuan Guo