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.