An Efficient Adaptive Image Enhancement Method in Wavelet Domain for Handwritten Document

Han-Yen Tu; Chih-Hsien Hsia; Hoang Thi Huong Giang

doi:10.6180/jase.2016.19.3.14

An Efficient Adaptive Image Enhancement Method in Wavelet Domain for Handwritten Document

Han-Yen Tu¹, Chih-Hsien Hsia This email address is being protected from spambots. You need JavaScript enabled to view it.¹ and Hoang Thi Huong Giang²

¹Department of Electrical Engineering, Chinese Culture University, Taipei, Taiwan 111, R.O.C.
²Graduate Institute of Digital Mechatronic Technology, Chinese Culture University, Taipei, Taiwan 111, R.O.C.

Received: January 18, 2016
Accepted: March 25, 2016
Publication Date: September 1, 2016

Download Citation: ||https://doi.org/10.6180/jase.2016.19.3.14

ABSTRACT

In this study, a new method, called adaptive image enhancement (AIE), is used to enhance handwritten document images, such as historical documents. An AIE method is proposed to denoise handwritten documents in a wavelet domain, which differs from others methods in two aspects: Firstly, modified contrast limited adaptive histogram equalization (MCLAHE) is used to equalize the contrast of an image by cutting the histogram at some threshold, and then equalization is used. Secondly, the image is improved by using directional discrete wavelet transform (D2 WT) enhancing for foreground and interfering strokes, respectively. As a result, this method not only removes the interfering strokes or visible watermarks in the background information, but also significantly increases the readability of handwritten document images.

Keywords: Wavelet Transforms, Histogram Equalization, Image Enhancement, Handwritten Document, Visible Watermark

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