1. A method for correcting for background noise in a frame of image data, the method comprising: receiving the frame of image data from an image sensor having an array of image pixels and a plurality of optically black pixels, wherein the frame of image data includes first background signal values from the optically black pixels; grouping the first background signal values into blocks; calculating block average values based on the first background signal values included in each respective block; determining second background signal values for the image pixels in the array based on the block averages, wherein the second background signal values indicate an amount of background noise associated with the image pixels; generating corner background signal values for corner regions of the pixel array based on the block average values, wherein the corner regions of the pixel array are free of image pixels and optically black pixels; and applying the second background signal values to the frame of image data.