1 Introduction
Interest 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 for autonomous machine perception. This chapter has several objectives: (1)to define the scope of the field that we call image processing; (2)to give a historical perspective of the origins of this field; (3)to give an idea of the state of the art in image processing by examining some of the principal area in which it is applied; (4)to discuss briefly the principal approaches used in digital image processing; (5)to give an overview of the components contained in a typical, general-purpose image processing system; and (6) to provide direction to the books and other literature where image processing work normally is reporter.
1.1 What Is Digital Image Processing?
1 緒論
數(shù)字圖像處理方法的研究源于兩個(gè)主要應(yīng)用領(lǐng)域:其一是為了便于人們分析而對(duì)圖像信息進(jìn)行改進(jìn)；其二是為了使機(jī)器自動(dòng)理解而對(duì)圖像數(shù)據(jù)進(jìn)行存儲(chǔ)、傳輸及顯示。
1.1 數(shù)字圖像處理的概念
一幅圖像可定義為一個(gè)二維函數(shù)f(x, y)，這里x和y是空間坐標(biāo)，而在任何一對(duì)空間坐標(biāo)f(x, y)上的幅值f稱為該點(diǎn)圖像的強(qiáng)度或灰度。當(dāng)x，y和幅值f為有限的、離散的數(shù)值時(shí)，稱該點(diǎn)是由有限的元素組成的，沒一個(gè)元素都有一個(gè)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。
視覺是人類最高級(jí)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(jī)器則可覆蓋幾乎全部電磁波譜，從伽馬射線到無線電波。它們可以對(duì)非人類習(xí)慣的那些圖像源進(jìn)行加工，這些圖像源包括超聲波、電子顯微鏡及計(jì)算機(jī)產(chǎn)生的圖像。因此，數(shù)字圖像處理涉及各種各樣的應(yīng)用領(lǐng)域。