Patent ID: 8564697

Claim:
A method for calibrating a black level signal in a frame, comprising: applying a first calibration signal to a first set of black level signals associated with a first set of black pixels of the frame to generate a first set of adjusted black level signals; averaging a first set of digital values corresponding to the first set of adjusted black level signals; determining whether a first average value based on the first set of digital values has reached a target black level; if the first average value has not reached the target black level, then proceeding to determine a first calibration offset based on an accumulator step and a first difference between the first average value and the target black level; converting the first calibration offset to an analog signal; generating a second calibration signal based on the analog signal; applying the second calibration signal to a second set of black level signals associated with a second set of black pixels of the frame to generate a second set of adjusted black level signals; averaging a second set of digital values corresponding to the second set of adjusted black level signals; and determining whether a second average value based on the second set of digital values has reached the target black level and whether to proceed to determine a second calibration offset, wherein the second calibration offset is determined based on the accumulator step and a second difference between the second average value and the target black level.