2012图像处理定稿版答案.docVIP

2011 年 ~ 201第 2 学期 reduce the gray range [0,100] to [0,10], and change the gray range [100,200] to [10,245], and the gray range [200,255] to [245,255]. (8’). Answer: 2. Let’s code the symbols of an information source individually shown below. Please give the Huffman coding process and Huffman code results of each information source. Moreover, compute the average number of bits required to code the information data. (Note: the code for the larger probability is 0, the less one is 1. ) (16’) symbol Probability Huffman code 1 Huffman code 2 Huffman code 3 Huffman code 4 S0 0.5 1 0 0 0 S1 0.2 01 11 01 10 S2 0.15 001 100 000 110 S3 0.06 0001 1011 0011 1110 S4 0.05 00000 10100 00100 11110 S5 0.04 00001 10101 00101 11111 Answer: symbol Probability Huffman code 1 2 3 4 S0 0.5 0 0.5 0 0.5 0 0.5 0 0.5 0 S1 0.2 11 0.2 11 0.2 11 0.3 10 0.5 1 S2 0.15 100 0.15 100 0.15 100 0.2 11 S3 0.06 1011 0.09 1010 0.15 101 S4 0.05 10100 0.06 1011 S5 0.04 10101 If the Huffman code results are correct and the student gives the process of Huffman coding, he gets 12’. If the code results are correct without giving the process, he only gets 6’. its average code length： ==2.4 (4’) 3. Consider the image shown below Apply the sharpening filter H. And use the following approximation to compute gradient g=|G|, where G is the image filtered by H. Sketch gradient image g. (12’) Answer: (2’, if G is correct ,it also gets 2’) (3’) (7’) if g is correct, it also gets 12’. 4. Let , for =0,1,2,…, M-1 and =0,1,2,…,N-1,denote an MN image. Suppose the 2-D discrete Fourier transform of denoted by . Please give the equations of the 2-D discrete Fourier transform and its inverse discrete Fourier transform. In addition, please give the mathematic expressions of the Fourier spectrum, the phase angle of the transform and the power spectrum. (10’) Answer: The 2-D discrete Fourier transform and its inverse discrete Fourier transform are