Anti-geometric diffusion for adaptive thresholding and segmentation

We present a novel adaptive thresholding technique based upon an anisotropic diffusion model, which may be referred to as the anti-geometric heat flow. In contrast to its more popular counterparts (such as the geometric heat flow) which diffuse parallel to image edges, this model diffuses perpendicular to image edges, yielding surfaces which are naturally suited for adaptive thresholding and segmentation. While it is possible to apply this diffusion for a fixed amount of time to detect features, we discuss how to detect features during the diffusion process, thus avoiding much of the arbitrariness associated with choosing a single scale (and makes the most notorious problem associated with anisotropic diffusion methods, namely "when do you stop?" a moot point). We demonstrate the performance of this technique on both synthetic and real images, showing applications to thresholding written text and segmentation of medical images and scenes.