2. A method as in claim 1 , wherein binarizing each subimage comprises: performing Otsu's thresholding algorithm to determine a threshold for binarization; detecting if a subimage is blank; detecting when a subimage includes light text on a dark background; and detecting if a subimage has varying background and foreground.
7. A method as in claim 2 , wherein detecting if a subimage is blank comprises: analyzing between-class variance at which the threshold for binarization was determined; and determining that the subimage is blank when the variance is below the threshold.