A Fault-Tolerant Active Pixel Sensor to Correct In-Field Hot-Pixel Defects

Solid-state image sensors develop in-field defects in all common environments. Experiments have demonstrated the growth of significant quantities of hot-pixel defects that degrade the dynamic range of an image sensor and potentially limit low-light imaging. Existing software- only techniques for suppressing hot-pixels are inadequate because these defective pixels saturate at relatively low illumination levels. The redundant fault-tolerant active pixel sensor design is suggested to isolate point-like hot-pixel defects. Emulated hot-pixels have been induced in hardware implementations of this pixel architecture and measurements of pixel response indicate that it generates an accurate output signal throughout the sensor's entire dynamic range, even when standard pixels would be otherwise saturated by the hot defect. A correction algorithm repairs the final image by building a simple look-up table of illumination- response of a working pixel. In emulated hot-pixels, the true illumination value can be recovered with an error of plusmn5% under typical conditions.