國立臺灣大學電機工程學系暨研究所林宗男2006-07-252018-07-062006-07-252018-07-062003-07-31http://ntur.lib.ntu.edu.tw//handle/246246/7949本計劃是研究一個可適應性的多階層的 影像濾波方法，處理由於在不同設備上的影 像複製上所會出現的的人工圖樣及moiré pattern。我們將分析moiré pattern 在頻域及 時域上的形式，並發展一套階層式濾波的方 法，可有效的抑制moiré 的人工圖樣且能增 強影像輪廓。最後再將影像的邊緣分類，使 的濾波器能達到在影像輪廓明顯的區域及平 滑區域可以達到平穩轉換的效果，使的我們 能得到較高的影像品質。This paper describes a novel adaptivehierarchical- filtering technique to achieve highquality image enhancement when the image possesses the artifact of moiré pattern during the reproduction of the image by different computer peripherals such as color copier, or scanners plus printers. Commercial magazine images are halftoned images. Unacceptable noises and moiré distortion may result when halftone images are copied (i.e., scanned and printed). In this paper, we analyze the formation of moiré patterns in the frequency and spatial domain. Based on the analysis, a set of hierarchical filter is developed to suppress the moiré artifacts and enhance the image adaptively. The hierarchical filter consists of a set of variable-length low-pass filters and high-pass filters. The low-pass filters have a nice inheritance of canceling aliased low frequency components (moiré distortion). Highpass filtering is also applied to sharpen image edges. An image classifier is developed to determine that an edge is either a global true edge (for sharpening enhancement) or a local halftone’s micro-structural edge (for LPF for moiré reduction), so that adaptive filter technique can be applied to achieve the smooth transition between sharp edges and smooth halftone regions. Thus, we achieves overall high-quality output images. Experimental results have been shown the effectiveness of the presented technique that works well on wide combinations of above-mentioned 6 factors, which will be explained during the following sections, for high-quality magazine image reproduction.application/pdf134426 bytesapplication/pdfzh-TW國立臺灣大學電機工程學系暨研究所reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/7949/1/912219E002041.pdf