可適性階層多解析彩色影像處理與分析
Date Issued
2003-07-31
Date
2003-07-31
Author(s)
DOI
912219E002041
Abstract
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.
Publisher
臺北市：國立臺灣大學電機工程學系暨研究所
Type
report
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