Layout-aware limiarization for readability enhancement of degraded historical documents
Flávio Bertholdo, Eduardo Alves do Valle Junior, Arnaldo de Albuquerque Araújo · 2009
In this paper we propose a technique of limiarization (also known as thresholding or binarization) tailored to improve the readability of degraded historical documents. Limiarization is a simple image processing technique, which is employed in many complex tasks like image compression, object segmentation and character recognition. The technique also finds applications on itself: since it results in a high-contrast image, in which the foreground is clearly separated from the background, it can greatly improve the readability of a document, provided that other attributes (like character shape) do not suffer. Our technique exploits statistical characteristics of textual documents and applies both global and local thresholding. Under visual inspection on experiments made in a collection of severely degraded historical documents, it compares favorably with the state of the art.