Restoring high-resolution binary images for text enhancement

A new method for restoring high-resolution binary images is presented to improve legibility of low-resolution document images. The initially restored image is generated by simple techniques, and is then improved by integrating a variety of features obtained through image analysis. Missing strokes of characters are complemented based on topographic features. Contours of characters are then modified in terms of gradient magnitudes and curvatures along the contours. Finally, contours are beautified so that they look good to the human eye. The proposed method can deal with characters having complex structures such as Kanji, and entails relatively simple computation. Smoothness and linearity along contours are significantly improved and strokes are restored correctly. The proposed method also improves OCR accuracy.