• inverse halftoning;
  • multiple low-pass filters;
  • super-resolution image processing


This paper focuses on the inverse halftoning problem, that is, the problem of reconstructing continuous-tone images from halftone images of white and black pixels. In general, the problem does not have a unique solution, since halftoning is a many-to-one map from continuous-tone images to binary ones. To this problem, we provide a simple and useful inverse halftoning method, composed of two steps. The first step is to generate several grayscale images from the original halftone image and low-pass filters. The next step is to reconstruct a continuous-tone image from the multiple grayscale images by using super-resolution image processing. This method allows us to obtain good continuous-tone images which are comparable to the results of the existing methods. The validity of the proposed method is demonstrated by several experiments. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.