A Line Smoothing Method of Hand-Drawn Strokes Using Adaptive Moving Average for Illustration Tracing Tasks


IEICE TRANSACTIONS on Information and Systems   Vol.E95-D   No.11   pp.2704-2709
Publication Date: 2012/11/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E95.D.2704
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Computer Graphics
moving average,  illustration tracing,  smoothing hand-drawn lines,  computer graphics,  

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There are many web sites where net users can post and distribute their illustration images. A typical way to draw a digital illustration is first to draw rough lines on a paper and then to trace the lines on a graphics-tablet by hand. The input lines usually contain fluctuation due to hand-drawing, which limits the quality of illustration. Therefore, it is important to remove the fluctuation and to smooth the lines while maintaining sharp features such as corners. Although naive applications of moving average filters can smooth input lines, they may cause over-smoothing artifacts in which sharp features are lost by the filtering. This paper describes an improved line smoothing method using adaptive moving averages, which smoothes input lines while keeping high curvature points. The proposed method evaluates curvatures of input lines and adaptively controls the filter-size to reduce the over-smoothing artifacts. Experiments demonstrated advantages of the proposed method over the previous method in terms of achieving smoothing effect while still preserving sharp feature preservation.