題名: Document image segmentation and quality improvement by moir � pattern analysis 作者: J. C. Y. Yang;W. H. Tsai
貢獻者: Department of Information Communication
關鍵詞: Moir � pattern ;Halftone screen;Printed document;Document segmentation;Image scanning;Quality improvement;Fourier analysis;Conductor of screen sharing;Comb filter;Sampling;Logical filter
日期: 2000-07
上傳時間: 2009-11-25T02:31:11Z 出版者: Asia University
摘要: Moir� patterns are distortions on the results of scanning printed documents.
However, the patterns can be utilized in document image segmentation and quality improvement. The moir� phenomenon comes from sampling periodical structures in images, such as halftone screens, color components, and text galleys which often appear in printed magazines and newspapers. The generated moir�
patterns appear in the scanning result in the form of obvious periodical patterns, color skew, and color noise on the edges of artworks. The moir� pattern degrades the scanning result and makes document analysis more difficult. A new approach to document image segmentation and quality improvement by moir� pattern analysis is proposed. A scanning resolution, called the conductor of screen sharing, is proposed to control the moir� pattern. With the resolution, moir� patterns are generated and enhanced in certain designed areas in the frequency domain. Then, a logical filter, called the comb filter, is proposed to detect the moir� pattern. The new method, which is based on the sampling theory and moir� analysis in the frequency domain, is actually performed in the spatial domain by re-sampling and logical filtering. The proposed method can efficiently extract gray or color pictures, artworks, and text paragraphs in printed documents. Moreover, the moir� patterns on the segmented document components can be easily suppressed. The
suppression yields better image quality for further analysis and image compression.
Experimental results are shown to demonstrate the feasibility of the proposed approach.
