數(shù)字圖像處理(第一章)-資料下載頁
2025-05-02 08:16本頁面
【正文】 i(x,y) intensity of the incident light 0 i (x,y) r(x,y) the coefficient of the reflection, depend on the object light casts 0 r(x,y) 1 ?2022/5/25 Digital Image Processing 63 Take a picture as an example. f (x,y) Y X 2022/5/25 Digital Image Processing 64 Sampling Digitize the spatial coordinates ( pixel ) Quantizing Digitize the intensity function f (x,y) An image processed by sampling and quantizing is called the digital image. It is also the procedure from a continuous image to a discrete one. Uniform sampling If all sampled points are equal spaces Uniform quantizing If all greylevel intervals are the same ( From the darkest to the brightest ) 2022/5/25 Digital Image Processing 65 Suppose there are N pixels along horizontal direction X and M pixels along vertical direction Y. and there are L gray levels, a digital image cab be represented by the following matrix. ???????????????????????)1,1()1,1()0,1(........................................)1,1(........)1,1()0,1()1,0(........)1,0()0,0(),(MNfNfNfMfffMfffyxf2022/5/25 Digital Image Processing 66 For any point (x,y) in the digital image ? ?1,......1,0 ?? Nx ? ?1,......1,0 ?? My? ?1, . . . . . .1,0),( ?? LyxfUsually, 2nN ? 2mM ?and 2kL ?So the number, b, of bits required to store a digital image: kNMb ???2022/5/25 Digital Image Processing 67 As for the quality of a digital image, the larger are M, N and L, the better is the image. For a square image, we have M=N, so Usually mb N ?? 22022/5/25 Digital Image Processing 68 Question: What will happen to the image when we change the value of M or N? What will happen to the image when we change the value of L or k? We modify M and N, let them decrease gradually, but k is not be changed, let M=N=1024, M=N=512, M=N=256, M=N=128, M=N=64 and M=N=32, the results are shown as follows respectively. 2022/5/25 Digital Image Processing 69 2022/5/25 Digital Image Processing 70 When M and N are not changed, we let k=8,7 6,5,4,3,2,1 respectively, that is L=256, 128, 64, 32, 16, 8, 4 and 2 respectively, we get all images as shown on the right. 2022/5/25 Digital Image Processing 71 If we change M, N and k simultaneously, what will happen? Take the following three pictures for an example. 2022/5/25 Digital Image Processing 72 The result can be described as the following graph. 2022/5/25 Digital Image Processing 73 Questions amp。 Problems 1. What is DIP? 2. What are differences between DIP and Computer graphics?
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