光谱法分析迭代重建过程中的滤波
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摘要
应用光谱法讨论了滤波器及其滤波方案对重建效果的影响。数值模拟重建场,应用光谱法分析了1/4,1/5,1/8均值滤波器,1/5中值滤波器,1/3行、列滤波器,在内嵌、外置等情况下对代数迭代重建的场滤波效果的影响。结果发现:用代数迭代法重建的场含有较大噪声,需要平滑处理;采用1/4,1/5或1/8均值滤波器仅对迭代结果滤波,会严重降低重建精度;采用1/4,1/8均值滤波器内嵌在迭代过程中按一定的迭代次数滤波,可以在一定程度上改善重建精度;采用1/5中值滤波器内嵌在迭代过程中比相应的均值滤波器重建效果更好;内嵌1/5中值滤波器和均值滤波器交替滤波,效果比单一的滤波器滤波更好。采用不同的滤波器和滤波方案对重建结果的影响差别较大。
The effects of filters and filtering methods on the field reconstructed by algebraic reconstruction technique(ART) is discussed with spectroscopy.The field to be constructed was simulated with numerical simulation technique.The effects of many kinds of filters and filtering methods on the field reconstructed by ART were analyzed with spectroscopy.The filters used included quarter,fifth,eighth averaging filter,fifth center filter,and third row,column filter.The filtering methods included filter being inserted in the iterating process or set at its end.The averaging filter mentioned above meant that the value was(acquired) from the average of the four data,named quarter averaging filter,and so on.The fifth center filter meant that the value was acquired from the center,the third one in ascendant or descendant sequence of the five data.As a result,the authors found that a larger difference existed in the effects of different filters and filtering methods on the reconstructed field.First,the field reconstructed by ART contained much big noise and needed to be smoothed.Secondly,the reconstructive accuracy declined much when an averaging filter,such as quarter,fifth or eighth filter,was only set at the end of iterating process.Thirdly,the accuracy could be improved a little with a quarter or eighth averaging filter inserted in the iterating process and activated according to iterating times.Forthly,a better accuracy could be obtained with a fifth center filter inserted in the iterating process than with a fifth averaging one inserted.Fifthly,the best result in this work was obtained with a fifth averaging filter and a fifth center one inserted in the iterating process and activated alternately according to iterating times.
The effects of filters and filtering methods on the field reconstructed by algebraic reconstruction technique(ART) is discussed with spectroscopy.The field to be constructed was simulated with numerical simulation technique.The effects of many kinds of filters and filtering methods on the field reconstructed by ART were analyzed with spectroscopy.The filters used included quarter,fifth,eighth averaging filter,fifth center filter,and third row,column filter.The filtering methods included filter being inserted in the iterating process or set at its end.The averaging filter mentioned above meant that the value was(acquired) from the average of the four data,named quarter averaging filter,and so on.The fifth center filter meant that the value was acquired from the center,the third one in ascendant or descendant sequence of the five data.As a result,the authors found that a larger difference existed in the effects of different filters and filtering methods on the reconstructed field.First,the field reconstructed by ART contained much big noise and needed to be smoothed.Secondly,the reconstructive accuracy declined much when an averaging filter,such as quarter,fifth or eighth filter,was only set at the end of iterating process.Thirdly,the accuracy could be improved a little with a quarter or eighth averaging filter inserted in the iterating process and activated according to iterating times.Forthly,a better accuracy could be obtained with a fifth center filter inserted in the iterating process than with a fifth averaging one inserted.Fifthly,the best result in this work was obtained with a fifth averaging filter and a fifth center one inserted in the iterating process and activated alternately according to iterating times.
引文
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[7]SONG Yi-zhong,LI Zun-ying,ZHU Rui-fu,et al(宋一中,李尊营,朱瑞富,等).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2002,22(4):545.
[8]LI Zun-ying,LIU Fu-yi(李尊营,刘复义).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2004,24(2):132.
[9]SONG Yi-zhong,HE An-zhi(宋一中,贺安之).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2004,24(1):29.
[10]YAO Wei,LI Zhen-hua,HE An-zhi(姚卫,李振华,贺安之).Acta Optic Sinica(光学学报),2000,20(5):684.
[2]Herman G T.ed.Translated by YAN Hong-fan,et al(严洪范,等译).Image Reconstruction from Projections—The Fundamentals ofComputerized Tomography(由投影重建图象———CT的理论基础).Beijing:Science Press(北京:科学出版社),1985.92.
[3]WU Jin(吴津).Tomographic Fundamentals with Applications to Crosswell Seismics(层析基础及其在井间地震中的应用).Beijing:Petroleum Industry Press(北京:石油工业出版社),1997.15.
[4]ZHUANG Tian-ge(庄天戈).Principle and Algorithm of Computerized Tomography(CT原理与算法).Shanghai:Shanghai Jiaotong Uni-versity Press(上海:上海交通大学出版社),1992.4.
[5]LI Chun-fang,ZHANG Xin-feng,PAN Jin-hu,et al(李春芳,张新峰,潘金虎,等).Journal of Optoelectronics.Laser(光电子.激光),2002,13(7):726.
[6]WANG Zhen-dong,SHI Ming-quan,LI Zhen-hua,et al(王振东,石明全,李振华,等).Acta Optica Sinica(光学学报),2002,22(5):556.
[7]SONG Yi-zhong,LI Zun-ying,ZHU Rui-fu,et al(宋一中,李尊营,朱瑞富,等).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2002,22(4):545.
[8]LI Zun-ying,LIU Fu-yi(李尊营,刘复义).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2004,24(2):132.
[9]SONG Yi-zhong,HE An-zhi(宋一中,贺安之).Spectroscopy and Spectral Analysis(光谱学与光谱分析),2004,24(1):29.
[10]YAO Wei,LI Zhen-hua,HE An-zhi(姚卫,李振华,贺安之).Acta Optic Sinica(光学学报),2000,20(5):684.
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