Adaptive Deblurring for Camera-Based Document Image Processing

With increasing resolution of cameras on mobile devices and their computing capacity, camera-based document processing becomes more attractive. However, there are several unique challenges, one of which is defocus. It is common that a camera-captured image is blurred by variable amount of location-dependent defocus. To improve image quality, we developed a novel method to adaptively deblur camera-based document images. In this method, sub-images of interest are first extracted from the captured image, and a point-spread function is derived for each sub-image by analyzing the gradient information along edges. Then the sub-image is deblurred by its local point-spread function. Preliminary experimental results indicate that the proposed adaptive deblurring method significantly improves focusing quality as evaluated by both human observers and objective focus measures compared with single-PSI; deblurring.