外文翻譯--數(shù)字圖像處理方法的研究

1、<p><b>　　附　錄</b></p><p><b>　　附錄A　外文資料</b></p><p>　　The research of digital image processing technique</p><p>　　Introduction</p><p>　　Intere

2、st in digital image processing methods stems from two principal application areas: improvement of pictorial information for human interpretation; and processing of image data for storage, transmission, and representation

3、 for autonomous machine perception. This chapter has several objectives: (1)to define the scope ofthe field that we call image processing; (2)to give a historical perspective of the origins of this field; (3)to give an i

4、dea of the state of the art in image processing by exa</p><p>　　What Is Digital Image Processing?</p><p>　　An image may be defined as a two-dimensional function,f(x,y)，where x and y are</p>

5、;<p>　　spatial (plane) coordinates, and the amplitude of fat any pair of coordinates (x,y) is called the intensity or gray level of the image at that point. When x, y, and digital image. Tire field of digital imag

6、e processing refers to processing digital images by means of a digital computer. Note that a digital image is composed of a finite number of elements, each of which has a particular location and value. These elements are

7、 referred to as picture elements, image elements, pels, and pixels. Pixel </p><p>　　Vision is the most advanced of our senses, so it is not surprising that images play the single most important role in human

8、 perception. However, unlike human who are limited to the visual band of the electromagnetic (E11)spectrum, imaging machines cover almost the entire EM spectrum, ranging from gamma to radio waves. They can operate on ima

9、ges generated by sources that human are not accustomed to associating with image. these include ultrasound, electron microscopy, and computer-generated image</p><p>　　There is no general agreement among auth

10、ors regarding where image processing stops and other related areas, such as image analysis and computer vision, start ,sometimes a distinction is made by defining image processing as a discipline in which both the input

11、and output of a process are images. We believe this to be a limiting and somewhat artificial boundary. For example, under this definition, even the trivial task of computing tire average intensity of an image (which yiel

12、ds a single number) </p><p>　　There are no clear-cut boundaries in the continuum from image processing at one end to computer vision at the other. However，one useful paradigm is to consider three types of co

13、mputerized processes is this continuum: how-，mid-, and high-ever processes. low-level processes involve primitive operation such as image preprocessing to reduce noise, contrast enhancement, and image sharpening. A low-l

14、evel process is characterized by the fact that both its input and output are images.mid-level processin</p><p>　　Based on the preceding comments, we see that a logical place of overlap between image processi

15、ng and image analysis is the area of recognition of individual regions or objects in an image. Thus, what we call in this book digital image processing encompasses processes whose inputs and outputs are images and, in ad

16、dition,encompasses processes that extract attributes from images,up to and including the recognition of individual objects. As a simple illustration to clarify these concepts, consider t</p><p>　　The Origins

17、 of Digital Image Processing</p><p>　　One of the first applications of digital images was in the newspaper industry, when pictures~first sent by submarine cable between London and NewYork.Introduction of the

18、 Bartlane cable picture transmission system in the early 1920s reduced the time required to transport a picture across the Atlantic from more than a week to less than three hours.Specialized printing equipment coded pict

19、ures for cable transmission and then recondstruced on a telegragh printer fitted with typefaces simulating a ha</p><p>　　The idea of computer goes back to the invention of the abacus in Asia Mintor,more than

20、 5000 years ago. More recently, there were developments in the past two centuries that are the foundation of what we call computer today. However, the basisfor what we call a modem digital computer dates back to only the

21、 1940s with theintroduction by John von Neumann of two key concepts: (1) a memory to hold a stored program and data, and (2)conditional branching. There two ideas are the foundation of a central</p><p>　　(1)

22、 the invention of the transistor by Bell Laboratories in 1948;</p><p>　　(2) the development in the 1950s and 1960s of the high-level programming languages COBOL (Common Business-Oriented Language) and FORTRA

23、II,( Formula Translator);</p><p>　　(3) the invention of the integrated circuit (IC) at Texas Instruments in 1958;</p><p>　　(4) the development of operating system in the early 1960s;</p>

24、<p>　　(5)the development of the microprocessor (a single chip consisting of the central processing unit, memory, and input and output controls) by Inter in the early 1970s;</p><p>　　(6) introduction by

25、IBM ofthe personal computer in 1981;</p><p>　　(7) progressive miniaturization of components, starting with large scale integration (LI)in the late 1970s, then very large scale integration (VLSI) in the 1980s

26、, to the present use of ultra large scale integration (ULSI).</p><p>　　Concurrent with these advances were development in the areas of mass storage and display systems, both of which are fundamental requirem

27、ents for digital image processing. The first computers powerful enoueh to carry out meaningful image processing tasks appeared in the early 1960s. The birth of what we call digital image processing today can be traced to

28、 the availability of those machines and the onset of the apace program during that period. It took the combination of those two developments to </p><p>　　In parallel with space application, digital image pro

29、cessing techniques began in the late 1960s and early 1970s to be used in medical imaging, remote Earth resources observations, and astronomy. The invention in the early 1970s of computerized axial tomography (CAT), also

30、called computerized tomography (CT) for short, is one of the most important events in the application of image processing in medical diagnosis. Computerized axial tomogmphy is a process in which a ring of detectors encir

31、cles an</p><p>　　From：www.docin.com</p><p>　　數(shù)字圖像處理方法的研究</p><p><b>　　緒論</b></p><p>　　數(shù)字圖像處理方法的研究源于兩個主要應用領域:其一是為了便于人們分析而對圖像信息進行改進;其二是為了使機器自動理解而對圖像數(shù)據(jù)進行存儲、傳輸及顯

32、示。</p><p><b>　　數(shù)字圖像處理的概念</b></p><p>　　一幅圖像可定義為一個二維函數(shù)f(-, y),這里x和y是空間坐標，而在任何一對空間坐標f (x,y)上的幅值f稱為該點圖像的強度或灰度。當x, y和幅值f為有限的、離散的數(shù)值時，稱該點是由有限的元素組成的，沒一個元素都有一個特定的位置和幅值，這些元素稱為圖像元素、畫面元素或象素。象素是廣

33、泛用于表示數(shù)字圖像元素的詞匯。在第二章，將用更正式的術(shù)語研究這些定義。</p><p>　　視覺是人類最高級的感知器官，所以，毫無疑問圖像在人類感知中扮演著最重要的角色。然而，人類感知只限于電磁波譜的視覺波段，成像機器則剛覆蓋幾乎全部電磁波譜，從伽馬射線無線電波。它們可以對非人類習慣的那些圖像源進行加工，這些圖像源包括超聲波、電子顯微鏡及計算機產(chǎn)生的圖像。因此，數(shù)字圖像處理涉及各種各樣的應用領域。</p&g

34、t;<p>　　圖像處理涉及的范疇或其他相關領域(例如，圖像分析和計算機視覺)的界定在初創(chuàng)人之間并沒有一致的看法。有時用處理的輸人和輸出內(nèi)容都是圖像這一特點來界定圖像處理的范圍。我們認為這一定義僅是人為界定和限制。例如，在這個定義下，甚至最普通的計算一幅圖像灰度平均值的工作都不能算做是圖像處理。另一方面，有些領域(如計算機視覺)研究的最高目標是用計算機去模擬人類視覺，包括理解和推理并根據(jù)視覺輸人采取行動等。這一領域本身是人

35、工智能的分支，其目的是模仿人類智能。人工智能領域處在其發(fā)展過程中的初期階段，它的發(fā)展比預期的要慢得多，圖像分析(也稱為圖像理解)領域則處在圖像處理和計算機視覺兩個學科之間。近十年來，用光信息處理技術(shù)來進行數(shù)據(jù)加密和保障數(shù)據(jù)安全引起了相當?shù)年P注。Pefregier和Javidi最早發(fā)表了這個領域的研究論文。由于光學信息處理系統(tǒng)的高度并行性和超快處理速度，光學安全（optical security）技術(shù)對信息安全技術(shù)的發(fā)展具有重要的理論意義

36、和應用前景。另外，由于傅里葉光學信息處理系統(tǒng)具有讀寫復振幅的能力，而該復振幅信息由于其相位部分在普通光源下是無法看到的，故不能用僅對光強敏感的探測器。</p><p>　　1995 年， Philippe Refregier 等提出了雙隨機相位編碼方法，這種方法具有較好的安全性和魯棒性。從此光學加密技術(shù)進入快速發(fā)展時期。研究人員隨后提出了基于分數(shù)傅里葉變換的加密方法、基于菲涅耳變換的加密方法、基于聯(lián)合變換相關器的

37、加密系統(tǒng)、利用離軸數(shù)字全息的加密系統(tǒng)和利用相移干涉技術(shù)的加密系統(tǒng)等大量新的或改進的加密系統(tǒng)，使得光學加密領域的研究異彩紛呈。雖然目前光學加密技術(shù)的發(fā)展方興未艾，但其前景不可估量。總的來說，與電子手段相比，現(xiàn)有的光學加密系統(tǒng)還存在一些缺點：可實施性、靈活性與穩(wěn)定性都有待提高。</p><p>　　從圖像處理到計算機視覺這個連續(xù)的統(tǒng)一體內(nèi)并沒有明確的界線。然而，在這個連續(xù)的統(tǒng)一體中可以考慮三種典型的計算處理(即低級、

38、中級和高級處理)來區(qū)分其中的各個學科。低級處理涉及初級操作，如降低噪聲的圖像預處理，對比度增強和圖像尖銳化。低級處理是以輸人、輸出都是圖像為特點的處理。中級處理涉及分割(把圖像分為不同區(qū)域或目標物)以及縮減對目標物的描述，以使其更適合計算機處理及對不同日標的分類(識別)。中級圖像處理是以輸人為圖像，但輸出是從這些圖像中提取的特征(如邊緣、輪廓及不同物體的標識等)為特點的最后，高級處理涉及在圖像分析中被識別物體的總體理解，以及執(zhí)行與視覺相

39、關的識別函數(shù)(處在連續(xù)統(tǒng)一體邊緣)等。</p><p>　　根據(jù)上述討論，我們看到，圖像處理和圖像分析兩個領域合乎邏輯的重疊區(qū)域是圖像中特定區(qū)域或物體的識別這一領域。這樣，在本書中，我們界定數(shù)字圖像處理包括輸人和輸出均是圖像的處理，同時也包括從圖像中提取特征及識別特定物體的處理。舉一個簡單的文本自動分析方面的例子來具體說明這一概念。在自動分析文本時首先獲取一幅包含文本的圖像，對該圖像進行預處理，提取(分割)字符，

40、然后以適合計算機處理的形式描述這些字符，最后識別這些字符，而所有這些操作都在本書界定的數(shù)字圖像處理的范圍內(nèi)理解一頁的內(nèi)容可能要根據(jù)理解的復雜度從圖像分析或計算機視覺領域考慮問題。這樣，本書定義的數(shù)字圖像處理的概念將在有特殊社會和經(jīng)濟價值的領域內(nèi)通用在以下各章展開的概念是那些應用領域所用方法的基礎。</p><p><b>　　數(shù)字圖像處理的起源</b></p><p>

41、;　　數(shù)字圖像處理最早的應用之一是在報紙業(yè)，當時，圖像第一次通過海底電纜從倫敦傳往紐約。早在20世紀20年代曾引入Btutlane電纜圖片傳輸系統(tǒng)，把橫跨大西洋傳送一幅圖片所需的時間從一個多星期減少到3個小時為了用電纜傳輸圖片，首先要進行編碼，然后在接收端用特殊的打印設備重構(gòu)該圖片。剛才引用的數(shù)字圖像的例子并沒有考慮數(shù)字圖像處理的結(jié)果這主要是因為沒有涉及到計算機.因此，數(shù)字圖像處理的歷史與數(shù)字計算機的發(fā)展密切相關。事實上，數(shù)字圖像要求非

42、常大的存儲和計算能力，因此數(shù)字圖像處理領域的發(fā)展必須依靠數(shù)字計算機及數(shù)據(jù)存儲、顯示和傳輸?shù)认嚓P技術(shù)的發(fā)展。</p><p>　　計算機的概念可追溯到5000多年前中國算盤的發(fā)明.近兩個世紀以來的一些發(fā)展也奠定了計算機的基礎.然而，現(xiàn)代計算機的基礎還要回溯到20世紀40年代由約翰·馮。諾依曼提出的兩個重要概念:(1)保存程序和數(shù)據(jù)的存儲器;(2)條件分支。這兩個概念是中央處理單元(CPU)的基礎。今天，它

43、是計算機的心臟從馮·諾依曼開始，引發(fā)了一系列重要技術(shù)進步，使得計算機以強大的功能用于數(shù)字圖像處理領域</p><p>　　簡單說，這些進步可歸納為如下幾點：</p><p>　　(1)1948年貝爾實驗室發(fā)明了晶體三極管；</p><p>　　(2)20世紀50年代到20世紀60年代高級編程語言(如COBOL和FORTRAN)的開發(fā)；</p>

44、<p>　　(3)1958年得州儀器公司發(fā)明了集成電路(IC);M2。世紀60年代早期操作系統(tǒng)的發(fā)展；</p><p>　　(4)1981年IBM公司推出了個人計算機;M20世紀70年代出現(xiàn)的大規(guī)模集成電路(LT)所引發(fā)的元件微小化革命，20世紀80年代出現(xiàn)了YLSI(超大規(guī)模集成電路)，現(xiàn)在已出現(xiàn)了ULSIo,伴隨著這些技術(shù)進步，大規(guī)模的存儲和顯示系統(tǒng)也隨之發(fā)展起來。這兩者均是數(shù)字圖像處理的基礎。&

45、lt;/p><p>　　第一臺可以執(zhí)行有意義的圖像處理任務的大型計算機出現(xiàn)在20世紀60年代，早期數(shù)字圖像處理技術(shù)的誕生可追溯至這一時期這些機器的使用和空間項目的開發(fā)，這兩大發(fā)展把人們的注意力集中到數(shù)字圖像處理的潛能上。利用計算機技術(shù)改善空間探測器發(fā)回的圖像的工作，始于1964年美國加利福尼亞的噴氣推進實驗室。當時由“旅行者7號”衛(wèi)星傳送的月球圖像由一臺計算機進行了處理，以校正航天器上電視攝像機中各種類型的圖像畸變進

46、行空間應用的同時，數(shù)字圖像處理技術(shù)在20世紀60年代末和20世紀70年代初開始用于醫(yī)學圖像、地球遙感監(jiān)測和天文學等領域。早在20世紀70年代發(fā)明的計算機軸向斷層術(shù)(CAT)[簡稱計算機斷層(CT)」是圖像處理在醫(yī)學診斷領域最重要的應用之一。計算機軸向斷層術(shù)是一種處理方法，在這種處理中，一個檢測器環(huán)圍繞著一個物體(或病人)，并且一個x射線源繞著物體旋轉(zhuǎn)。X射線穿過物體并由位于對面環(huán)中的相應檢測器收集起來當X射線源旋轉(zhuǎn)時，重復這一過程.斷層