Patent ID: 8622302

Claim:
A method of compensating for fixed pattern noise in an image sensor of an optical data reader, the method comprising: capturing a dark image using the image sensor, the dark image comprising a negligible amount of scene information to thereby provide an estimate of fixed pattern noise in the image sensor, the dark image having a corresponding first exposure time; storing the dark image; capturing an illuminated image comprising optical data from a read area using the image sensor, the illuminated image having a corresponding second exposure time, wherein the second exposure time exceeds the first exposure time; subtracting the dark image from the illuminated image to generate a compensated image comprising optical data that is, at least partially, compensated for fixed pattern noise in the image sensor; during normal operation of the optical data reader, detecting a change in a condition that affects the fixed pattern noise; based upon detecting the change in the condition, capturing a new dark image and replacing the dark image with the new dark image; and subtracting the new dark image from a subsequently captured illuminated image to generate a subsequent compensated image.