| 摘要 |
A method for correcting column Fixed Pattern Noise (FPN) in an image sensor offers a compromise between speed and precision for calculating column FPN offsets. The present correction technique is digital, and is applied after the pixel signal voltages have been digitized by an ADC. A first Optical Black (OB) pixel is sampled and compared to a target level. An offset is stored, and an appropriate push-size is determined. Additional OB pixels are sampled and the offset is applied. The push-size is increased or decreased depending upon whether the pixel signal with the applied offset is above or below a target value. This new offset value is written to memory, and the push-size is reduced, and the process is repeated until the last OB pixel has been processed. The resulting offset is applied to the signal pixels in a column. The primary advantage of this approach is that within a single frame, a good estimate of the column offset is made which is not as affected by outlier pixels (such as "hot" or "flashing" pixels). |
