Patent ID: 8228403

Claim:
A method for compensating for column fixed pattern noise in an image sensor, wherein the image sensor includes a plurality of photoactive pixels and a plurality of dark reference pixels arranged in rows and columns to form a pixel array, the method comprising: reading out, at a first gain level of pixel readout circuitry, dark signals from multiple dark reference pixels in each column; determining a column offset correction (“COC”) for one or more columns in the pixel array using the dark signals read out at the first gain level; generating second gain COC by scaling the COC in response to capturing a first image at a second gain level of the pixel readout circuitry, wherein the first image is generated by a first image capture at the second gain level since turning on the image sensor; and applying the second gain COC to subsequent images captured at the second gain level, wherein the subsequent images are captured prior to a power cycling of the image sensor.