Dynamic window construction for the binarization of barcode images captured by mobile phones

It is difficult to directly apply existing binarization methods to the barcode images captured by mobile devices under uncontrolled lighting conditions. Employing a fix-sized window to locally binarize the image cannot handle the situation when small and large objects co-exist in an image. This paper proposes a novel scheme to dynamically determine the size of the binarization window, which changes with the presence of the high gradient pixels in a search window centering the processing pixel. The proposed method has demonstrated its capability in handling objects of different sizes and the uneven illumination problem. Further, it is not constrained to certain barcode types. Experimental results conducted on 330 images captured using five mobile phones in indoor and outdoor environments achieve about 93% recognition rate evaluated using a barcode decoder. Comparisons with some existing approaches show its superior binarization performance.