Thresholding color images of historical documents with preservation of the visual quality of graphical elements

Article type: Research Article

Authors: Roe, E. | Mello, C.A.B.^*

Affiliations: Centro de Informática, Universidade Federal de Pernambuco, Cidade Universitária, Recife, Brazil

Correspondence: [*] Corresponding author: C.A.B. Mello, Centro de Informática, Universidade Federal de Pernambuco, Av. Jornalista Anibal Fernandes, s/n, Cidade Universitária, Recife, Brazil. E-mail: [email protected].

Abstract: A new thresholding algorithm is introduced for images of historical documents containing graphical elements as drawings. The major idea is to improve the binarization process such that the understanding of the drawings is not lost in the final bi-level image and the text areas are completely preserved for further recognition. As quality is a subjective matter, the algorithm allows non-specialized user interference in order to achieve the expected quality of the final image. The proposed method achieved satisfactory visual results when compared to other state-of-the-art thresholding algorithms. As a consequence of the algorithm, there is also a black ink economy in the printing of the images if compared with a halftoning printing of a grayscale image. This algorithm ranked the fourth position at H-DIBCO 2016 (the handwritten documents version of the annual Document Image Binarization COntest).

Keywords: Thresholding, historical documents, graphical elements, visual quality

DOI: 10.3233/ICA-180562

Journal: Integrated Computer-Aided Engineering, vol. 25, no. 3, pp. 261-272, 2018