Enhancement of fax documents using a binary angular representation

In this paper, we explore a new approach to enhancing fax documents using a binary directional filter bank (DFB). The process of sending fax documents often results in distortions that are visible in the form of spurious point noise and ragged edges. We propose a new approach that remains in the binary domain for the entire process. Conventional directional filter banks provide representations that delineate the directional components in the text letters enabling edges and contours to be smoothed appropriately. Our binary DFB receives a binary input and outputs a binary image comprised of directional components. With proper weighting of the subbands, the synthesis section can suppress the information of the artifacts in the output image. This paper provides a description of a new binary DFB and its application to enhancing text that has been degraded by the faxing process.