SHOCK FILTER-BASED DIFFUSION FIELDS — APPLICATION TO GRAYSCALE CHARACTER IMAGE PROCESSING

Abstract

In this article, the new concept of diffusion fields based on partial differential equations is applied to character image processing. Specific diffusion fields are developed according to character image structures and features, depending, on the scope of application. Doing so allows the application of a straightforward one-dimensional numerical scheme to image enhancement, erosion, dilation and thinning. The strength of this approach is the flexibility brought by the diffusion field, which can be defined taking into account specific difficulties of grayscale character images with a minimum of prior information. Thus, the application of the algorithm is shown to be robust to singularity points, the creation of spurious branches, variations in stroke thickness and intensity, multimodality, noise and image background patterns. The resulting enhanced images are noise free with sharp edges and the local typical intensity levels preserved. Thinned characters are connected skeletons located on the ridge of the initial character. Again, the typical intensity of the character and background are preserved.