第五章 正弦稳态电路分析 第一节 正弦信号的基本概念 5.1.1 正弦信号的三要素 5.1.2 正弦信号的相位差 5.1.3 正弦信号的有效值
第二章 離散餘弦轉換
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Transcript of 第二章 離散餘弦轉換
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(Discrete Cosine Transformation ,DCT) (data hiding)
2.1 2.2 2.3
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2.1
1. (Discrete Wavelet Transformation , DWT) 2. (Discrete Cosine Transformation , DWT)
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2.12.22.316DCT
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2.1DCT0~15
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2.2DCT
(wave number) N 0~15
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2.302220(basis wave)00
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(frequency domain)2.10(Direct Current , DC)(Altermating Current , AC)
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2.2
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2.2.1(Forward Discrete Cosine Transformation , FDCT)(Inverse DCT , IDCT)FDCTIDCT
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2.2.18*8(block)2.4[4]FDCT128IDCT128
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O(x,y)(x,y)f(x,y)O(x,y)128D(i,j)(I,j)(D(I,j) | i=0 to N-1j=0 to N=1)N*N(f(x,y) | i=0 to N-1j=0 to N-1)FDCT
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2.2.1FDCTIDCTFDCTIDCT(truncation error)
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2.2.2 (FDCT)
(IDCT)
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2.2.3 8*8(0,0)aIDCT8*88*8DCT(basis image)b(0,0)
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(0,1)IDCT8*8(0,1)(7,7)8*86464*64DCT(basis image of 2D DCT)
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2.2
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DCT
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DCTACDC(0,0)0(0,0)(DC)(0,0)(AC)
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FDCT(2.1)(0,0)
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DCT(low frequency)(high frequency)(medium frequency)DC
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DCT2.9DCDC
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(vertical edge)(horizontal edges)(diagonal edges)
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(horizontal energy)(vertiacl energy)(diagonal energy)
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abbadc
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2.2.4 FDCT IDCT
8*8
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2.23(0,0)2000(0,0)200IDCT2.23
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2.25(0,7)2000(0,7)200IDCT2.25
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2.27(7,0)2000(7,0)200IDCT2.27
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2.29FDCTDC(7,7)
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2.3012128128128IDCT3IDCT32.29IDCT
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200(0,0)200(7,7)
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2.3