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研究生:魏誌成
研究生(外文):Wei, Chih Cheng
論文名稱:改善污染透鏡成像之影像還原
論文名稱(外文):Image Restoration from Distortion Caused by Polluted Lenses in an Imaging System
指導教授:周本生
指導教授(外文):Chow, Ben Shen
學位類別:碩士
校院名稱:國立中山大學
系所名稱:電機工程研究所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:1994
畢業學年度:82
語文別:英文
論文頁數:69
中文關鍵詞:影像還原光學轉移函數
外文關鍵詞:Image RestorationOptical Transfer Function
相關次數:
  • 被引用被引用:0
  • 點閱點閱:66
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在光學影像系統中,透鏡易遭受污染而使得成像品質受到破壞,且此污染
透鏡可以等效於一完美透鏡緊貼著一污染薄膜。我們提出一個污染模式,
假設污點中心是呈波以松分佈( Poisson- distribution )且具重疊性質
,各污點半徑與透光率皆互相獨立隨機變化。由於各個污點透光率是乘積
性的,我們稱之為傳輸雜訊(transmittance noise),和相關研究的模式
比較,我們的模式更具實際性與合理性。我們不僅求得成像系統之平均光
學轉移函數( OTF ) ;進一步地,我們求得光學轉移函數之變異數,光學
轉移函數之變異數對於影像還原方法的設計及影像品質的分析有其重要之
地位。在求取光學轉移函數之變異數時,我們遇到了一個極為複雜的四重
積分,藉助解析幾何,我們簡化四重積分成為二重積分,使得計算量大大
減少。  採用電腦,我們模擬污染影像系統,求得模擬之光學轉移函數
且把模擬結果與理論分析做一比較。最後,我們利用光學轉移函數及其變
異數,設計出兩個影像還原的方法。

Lenses in an optical imaging system are liable to defection
such as pollution and thus deteriorates the imaging quality. To
study the effects on imaging quality, the polluted lens can be
verified equivalent to a polluted random screen set against a
normal lens. In our model, the defects on random screen are
assumed Poisson -distributed and can be overlapped with a
random size and trans- mittance. The effect of transmittance
for every individual defect is multiplicative, then, the
transmittance of the random screen is computed as a product of
Poisson-distributed-centered random function. This effect is
named as transmittance noise that was first introduced by Chow.
To compare with other models of related research, our model is
more reasonable and practical. We compute not only the average
optical transfer function (OTF) but the variance of the OTF for
imaging system. The variance of the OTF is computed for quality
analysis or restoration method designs, for the variance of the
OTF is importance in image rest- oration if it is significant
in value. Therefore, the variance at least stands as an
indicator for determining the image restorati- on method. The
computation of this statistics involves a prohibi- tive
fourfold integral computation. By the help of analytic geom-
etry, we simplify the fourfold integration to double
integration. Thus, the computation for the variance of the OTF
is a first att- empt in related researches. We simulate a
polluted optical imaging system in computer to perform the
experiments and check with our computed result from theory.
Finally, the distorted image is restored by two techniq- ues
that are designed by mean of the average OTF and the variance
of the OTF.

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