A near exact image expansion scheme for bi-level images

Exact bi-level image expansion techniques are required for a wide range of applications such as cartography, calligraphy, medical images, remote sensing, and satellite imagery. Among the methods proposed in the literature are (a) pixel replication; (b) area sizing; (c) interpolation and spline methods; and (d) DCT-based techniques. All these methods generate distortion and noticeable degradation in the quality of images especially around edges. We introduce a new image expansion scheme that produces significantly improved expanded and/or reduced images and maintains high quality edges. This scheme uses an elaborate look-up table that is based on look-ahead-and-back procedures for each pixel and maintains a memory of the pixels´ chain code connectivity. The experimental simulation results show that the resized images of the proposed scheme are aesthetically and objectively much better than those of the other methods.