计算机辅助设计与图形学学报
計算機輔助設計與圖形學學報
계산궤보조설계여도형학학보
JOURNAL OF COMPUTER-AIDED DESIGN & COMPUTER GRAPHICS
2009年
11期
1612-1617
,共6页
Contourlet变换%易操纵金字塔%方向滤波器组%图像降噪
Contourlet變換%易操縱金字塔%方嚮濾波器組%圖像降譟
Contourlet변환%역조종금자탑%방향려파기조%도상강조
Contourlet transform%steerable pyramid%directional filter banks%image denoising
针对Contourlet变换基图像不具备局部频率特性的缺点,分析了在频域楔形支撑区域外部出现潜在混叠的原因,并结合易操纵金字塔结构的优良特性,提出一种改进结构的Contourlet变换.该变换采用易操纵金字塔替换了原变换的拉普拉斯金字塔,保证了其平移不变性.非线性逼近实验和基图像分析的结果表明,该变换能够稀疏表示图像,避免了频域出现混叠.去噪实验结果表明,改进结构的Contourlet变换可以有效地提高去噪图像的峰值信噪比和去噪图像质量.
針對Contourlet變換基圖像不具備跼部頻率特性的缺點,分析瞭在頻域楔形支撐區域外部齣現潛在混疊的原因,併結閤易操縱金字塔結構的優良特性,提齣一種改進結構的Contourlet變換.該變換採用易操縱金字塔替換瞭原變換的拉普拉斯金字塔,保證瞭其平移不變性.非線性逼近實驗和基圖像分析的結果錶明,該變換能夠稀疏錶示圖像,避免瞭頻域齣現混疊.去譟實驗結果錶明,改進結構的Contourlet變換可以有效地提高去譟圖像的峰值信譟比和去譟圖像質量.
침대Contourlet변환기도상불구비국부빈솔특성적결점,분석료재빈역설형지탱구역외부출현잠재혼첩적원인,병결합역조종금자탑결구적우량특성,제출일충개진결구적Contourlet변환.해변환채용역조종금자탑체환료원변환적랍보랍사금자탑,보증료기평이불변성.비선성핍근실험화기도상분석적결과표명,해변환능구희소표시도상,피면료빈역출현혼첩.거조실험결과표명,개진결구적Contourlet변환가이유효지제고거조도상적봉치신조비화거조도상질량.
A major drawback of the Contourlet transform is that its basis images are not localized in the frequency domain.After analyzing the cause of frequency domain aliasing and many fine properties of the steerable pyramid,an improved Contourlet transform is proposed to overcome this problem.The proposed transform employs the steerable pyramid instead of the Laplacian pyramid to complete multiscale decomposition,which makes the transform shift invariant.By doing nonlinear approximation experiment and an analysis of the basis images,it is concluded that this transform can sparsely express images and avoid frequency domain aliasing.Our image denoising experimental results show that the proposed transform outperforms the original Contourlet transform in terms of both the peak signal noise rate (PSNR) and the visual quality.