Progressive encoding of facsimile images using edge decomposition (PED)

The authors present a method for progressive encoding of two-tone images which is based on an edge-decomposition algorithm. By recursively applying an image decomposition algorithm to a facsimile image, the latter can be reduced to an initial low-resolution replica plus a sequence of supplementary fields that upgrade the initial replica to its original form with successive resolution doublings. This encoding scheme allows comparatively rapid presentation of a replica on a document monitor, with enhancement to better resolution over time. The compression efficiency is equal to or better than that of the current CCITT group IV two-dimensional standard encoding