1. A method to find a specified number of corners in a digital image, the method comprising: receiving the digital image containing a plurality of candidate corners; calculating a threshold score (S) comprising a maximum of a brightness score (S B ) and a darkness score (S D ), using a set of non-iterative min-max operations, for each of a plurality of center pixels to form a plurality of scores, wherein each center pixel corresponds to a distinct individual candidate corner in the plurality of candidate corners, wherein for each candidate corner: the threshold score (S) comprises a maximum of a brightness score (S B ) and a darkness score (S D ); the brightness score (S B ) and the darkness score (S D ) each comprises a difference between an intensity of pixels; and the intensity of pixels comprises a minimum intensity, for the brightness score (S B ), or a maximum intensity, for the darkness score (S D ), of intensities of the pixels; sorting, by the plurality of scores, the plurality of candidate corners to form a sorted list; and selecting corner locations sequentially from the sorted list based on the specified number of corners.