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📁 数字图象处理入门,非常好的书！！！！推荐！
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</v:shape><![endif]--><![if !vml]><img width=76 height=23
src="./chp7.files/image001.gif" v:shapes="_x0000_i1025"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>和一幅图象</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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src="./chp7.files/image002.gif" v:shapes="_x0000_i1026"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>。不难发现原图中左边暗，右边亮，中间存在着一条明显的边界。进行模板操作后的结果如下：</span><sub><span
lang=ZH-CN style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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src="./chp7.files/image003.gif" v:shapes="_x0000_i1027"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>。</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>可以看出，第</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>3</span><span
lang=ZH-CN style='font-size:10.5pt'>、</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>4</span><span lang=ZH-CN style='font-size:10.5pt'>列比其他列的灰度值高很多，人眼观察时，就能发现一条很明显的亮边，其它区域都很暗，这样就起到了边沿检测的作用。</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>为什么会这样呢？仔细看看那个模板就明白了，它的意思是将右邻点的灰度值减左邻点的灰度值作为该点的灰度值。在灰度相近的区域内，这么做的结果使得该点的灰度值接近于</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>0</span><span
lang=ZH-CN style='font-size:10.5pt'>；而在边界附近，灰度值有明显的跳变，这么做的结果使得该点的灰度值很大，这样就出现了上面的结果。</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>这种模板就是一种边沿检测器，它在数学上的涵义是一种基于梯度的滤波器，又称边沿算子，你没有必要知道梯度的确切涵义，只要有这个概念就可以了。梯度是有方向的，和边沿的方向总是正交</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>(</span><span
lang=ZH-CN style='font-size:10.5pt'>垂直</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>)</span><span lang=ZH-CN style='font-size:10.5pt'>的，例如，对于上面那幅图象的转置图象，边是水平方向的，我们可以用梯度是垂直方向的模板</span><sub><span
lang=ZH-CN style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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</v:shape><![endif]--><![if !vml]><img width=36 height=75
src="./chp7.files/image004.gif" v:shapes="_x0000_i1028"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>检测它的边沿。</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>例如，一个梯度为</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>45</span><span
lang=ZH-CN style='font-size:10.5pt'>度方向模板</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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</v:shape><![endif]--><![if !vml]><img width=91 height=75
src="./chp7.files/image005.gif" v:shapes="_x0000_i1029"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>，可以检测出</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>135</span><span lang=ZH-CN style='font-size:
10.5pt'>度方向的边沿。</span><span style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><b><span style='font-size:10.5pt;
font-family:"Times New Roman"'>1.</span></b><b><span style='font-size:7.0pt;
font-family:"Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></b><b><span style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel</span></b><b><span
lang=ZH-CN style='font-size:10.5pt'>算子</span></b><span style='font-size:10.5pt;
font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>在边沿检测中，常用的一种模板是</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel </span><span
lang=ZH-CN style='font-size:10.5pt'>算子。</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>Sobel </span><span lang=ZH-CN style='font-size:
10.5pt'>算子有两个，一个是检测水平边沿的</span><sub><span lang=ZH-CN style='font-size:10.5pt;
font-family:"Times New Roman"'> </span></sub><sub><span style='font-size:10.5pt;
font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape id="_x0000_i1030"
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 <v:imagedata src="./chp7.files/image006.gif" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image012.gif"/>
</v:shape><![endif]--><![if !vml]><img width=103 height=75
src="./chp7.files/image006.gif" v:shapes="_x0000_i1030"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>；另一个是检测垂直平边沿的</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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</v:shape><![endif]--><![if !vml]><img width=88 height=75
src="./chp7.files/image007.gif" v:shapes="_x0000_i1031"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>。与</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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 <v:imagedata src="./chp7.files/image008.gif" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image016.gif"/>
</v:shape><![endif]--><![if !vml]><img width=100 height=75
src="./chp7.files/image008.gif" v:shapes="_x0000_i1032"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>和</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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 <v:imagedata src="./chp7.files/image009.gif" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image018.gif"/>
</v:shape><![endif]--><![if !vml]><img width=81 height=75
src="./chp7.files/image009.gif" v:shapes="_x0000_i1033"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>相比，</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>Sobel</span><span lang=ZH-CN style='font-size:
10.5pt'>算子对于象素的位置的影响做了加权，因此效果更好。</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span style='font-size:10.5pt;font-family:
"Times New Roman"'>Sobel</span><span lang=ZH-CN style='font-size:10.5pt'>算子另一种形式是各向同性</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel(Isotropic Sobel)</span><span
lang=ZH-CN style='font-size:10.5pt'>算子，也有两个，一个是检测水平边沿的</span><sub><span
lang=ZH-CN style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
 id="_x0000_i1034" type="#_x0000_t75" alt="" style='width:86.25pt;height:60pt'>
 <v:imagedata src="./chp7.files/image010.gif" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image020.gif"/>
</v:shape><![endif]--><![if !vml]><img width=115 height=80
src="./chp7.files/image010.gif" v:shapes="_x0000_i1034"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>，另一个是检测垂直平边沿的</span><sub><span lang=ZH-CN
style='font-size:10.5pt;font-family:"Times New Roman"'> </span></sub><sub><span
style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
 id="_x0000_i1035" type="#_x0000_t75" alt="" style='width:84pt;height:56.25pt'>
 <v:imagedata src="./chp7.files/image011.gif" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image022.gif"/>
</v:shape><![endif]--><![if !vml]><img width=112 height=75
src="./chp7.files/image011.gif" v:shapes="_x0000_i1035"><![endif]></span></sub><span
lang=ZH-CN style='font-size:10.5pt'>。各向同性</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>Sobel</span><span lang=ZH-CN style='font-size:
10.5pt'>算子和普通</span><span style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel</span><span
lang=ZH-CN style='font-size:10.5pt'>算子相比，它的位置加权系数更为准确，在检测不同方向的边沿时梯度的幅度一致。</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p style='margin:0cm;margin-bottom:.0001pt;text-align:justify;text-justify:
inter-ideograph;line-height:18.0pt'><span lang=ZH-CN style='font-size:10.5pt'>下面的几幅图中，图</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>7.1</span><span
lang=ZH-CN style='font-size:10.5pt'>为原图；图</span><span style='font-size:10.5pt;
font-family:"Times New Roman"'>7.2</span><span lang=ZH-CN style='font-size:
10.5pt'>为普通</span><span style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel</span><span
lang=ZH-CN style='font-size:10.5pt'>算子处理后的结果图；图</span><span style='font-size:
10.5pt;font-family:"Times New Roman"'>7.3</span><span lang=ZH-CN
style='font-size:10.5pt'>为各向同性</span><span style='font-size:10.5pt;font-family:
"Times New Roman"'>Sobel</span><span lang=ZH-CN style='font-size:10.5pt'>算子处理后的结果图。可以看出</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel</span><span
lang=ZH-CN style='font-size:10.5pt'>算子确实把图象中的边沿提取了出来。</span><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><span style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
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 <v:imagedata src="./chp7.files/image012.jpg" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image024.jpg"/>
</v:shape><![endif]--><![if !vml]><img width=319 height=202
src="./chp7.files/image012.jpg" v:shapes="_x0000_i1036"><![endif]><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><b><span lang=ZH-CN style='font-size:10.5pt'>图</span></b><b><span
style='font-size:10.5pt;font-family:"Times New Roman"'>7.1&nbsp;&nbsp;&nbsp;&nbsp;
</span></b><b><span lang=ZH-CN style='font-size:10.5pt'>原图</span></b><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><span style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
 id="_x0000_i1037" type="#_x0000_t75" alt="" style='width:239.25pt;height:150.75pt'>
 <v:imagedata src="./chp7.files/image013.jpg" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image026.jpg"/>
</v:shape><![endif]--><![if !vml]><img width=319 height=201
src="./chp7.files/image013.jpg" v:shapes="_x0000_i1037"><![endif]><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><b><span lang=ZH-CN style='font-size:10.5pt'>图</span></b><b><span
style='font-size:10.5pt;font-family:"Times New Roman"'>7.2&nbsp;&nbsp;&nbsp;&nbsp;
</span></b><b><span lang=ZH-CN style='font-size:10.5pt'>普通</span></b><b><span
style='font-size:10.5pt;font-family:"Times New Roman"'>Sobel</span></b><b><span
lang=ZH-CN style='font-size:10.5pt'>算子处理后的结果图</span></b><span style='font-size:
10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><b><span style='font-size:10.5pt;font-family:"Times New Roman"'><!--[if gte vml 1]><v:shape
 id="_x0000_i1038" type="#_x0000_t75" alt="" style='width:237pt;height:150pt'>
 <v:imagedata src="./chp7.files/image014.jpg" o:href="http://www-scf.usc.edu/~flv/ipbook/chap07.files/image028.jpg"/>
</v:shape><![endif]--><![if !vml]><img width=316 height=200
src="./chp7.files/image014.jpg" v:shapes="_x0000_i1038"><![endif]></span></b><span
style='font-size:10.5pt;font-family:"Times New Roman"'><o:p></o:p></span></p>

<p align=center style='margin:0cm;margin-bottom:.0001pt;text-align:center;
line-height:18.0pt'><b><span lang=ZH-CN style='font-size:10.5pt'>图</span></b><b><span
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