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一種基于多尺度分析的CT圖像邊緣檢測(cè)方法

An Approach of Edge Detection for CT Images Based on Multiscale Analysis

作者: 嚴(yán)華剛  李海云 
單位:首都醫(yī)科大學(xué)生物醫(yī)學(xué)工程學(xué)院(北京100069)
關(guān)鍵詞: 邊緣檢測(cè);多尺度分析;小波變換;CT圖像 
分類號(hào):
出版年·卷·期(頁(yè)碼):2010·29·6(603-607)
摘要:

為了準(zhǔn)確提取CT圖像中解剖組織幾何形態(tài)特征,提出了一種基于多尺度分析的CT圖像邊緣檢測(cè)方法。本文應(yīng)用多尺度分析中含有尺度因子的平滑函數(shù)的負(fù)導(dǎo)數(shù)作為小波,對(duì)CT圖像實(shí)施小波變換,并檢測(cè)小波變換的模局部極大值,完成基于模局部極大值的解剖組織輪廓特征表達(dá)。本文還討論了一種模局部極大值點(diǎn)的簡(jiǎn)單篩選方法,針對(duì)CT圖像噪聲較大的特點(diǎn),以模局部極大值的均方根乘以一個(gè)與尺度有關(guān)的因子作為模局部極大值的閾值,在不同尺度上獲得了清晰的邊緣信息。閾值處理后的模局部極大值圖表明,不同尺度下的邊緣檢測(cè)能給出大小不同的物體的邊緣信息。本方法能在有效抑制噪聲的基礎(chǔ)上,準(zhǔn)確提取感興趣解剖組織的幾何輪廓特征。

In order to correctly extract the geometric features of anatomies in CT images, we proposed an approach of edge detection for CT images based on multiscale analysis. The analysis for multiscale edge detection was implemented by using the negative derivatives of a smoothing function containing a scale factor as the wavelets to perform wavelet transform on CT images, and by locating the local modulus maxima of the transform to depict the geometric features of anatomies in the images. We also proposed a simple method for identifying the local modulus maxima points. In addition, in order to address the relatively large CT image noise, we utilized the thresholds, that were obtained by multiplying the means square root of all local modulus maxima with a factor related to the scale, and achieved clean edges consequently. The resulting pictures of local modulus maxima after the thresholding showed that the edge information of different objects of different sizes could be revealed by different edge detections under different scales. It is indicated that the method proposed can extract the geometric contour features of the anatomies of interest correctly after suppressing the noise effectively.

參考文獻(xiàn):

[1] Gonzalez  RC, Woods  RE. Digital Image Processing. 北京:電子工業(yè)出版社,2007:568.
[2] Canny  J. A Computational Approach to Edge Detection. IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986, PAMI8( 6): 679-697.
[3] Holschneider  M, Kronland-Martinet  R, Morlet  J,et al. Wavelets, Time Frequency Methods and Phase Space, chapter A Real-Time Algorithm for Signal Analysis with the Help of the Wavelet Transform, Berlin: Springer-Verlag, 1989: 289-297.
[4] Mallat S.A Wavelet Tour of Signal Processing. 3ed. Burlington: Academic Press: 2009: 240-241.

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