📄 chap08.htm
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<p style='line-height:18.0pt'><span> </span>
return FALSE;</p>
<p style='line-height:18.0pt'><span
lang=EN-US>}</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>指向该内存指针</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>lpSecondImgData=(LPBITMAPINFOHEADER)GlobalLock(hSecond);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>文件指针指到</span><span lang=EN-US>BITMAPINFOHEADER</span><span
style='font-family:宋体;"Times New Roman"'>结构开始的地方</span></p>
<p style='line-height:18.0pt'><span> </span>_llseek(hf,sizeof(BITMAPFILEHEADER),FILE_BEGIN);</p>
<p style='line-height:18.0pt'><span> </span>//<span
style='font-family:宋体;"Times New Roman"'>读入头信息和位图数据</span></p>
<p style='line-height:18.0pt'><span> </span>_lread(hf,(LPSTR)lpSecondImgData,BufSize);</p>
<p style='line-height:18.0pt'><span> </span>_lclose(hf);</p>
<p style='line-height:18.0pt'><span> </span>//<span
style='font-family:宋体;"Times New Roman"'>为结果图缓冲区分配内存</span></p>
<p style='line-height:18.0pt'><span> </span>if((hTempImgData=LocalAlloc(LHND,BufSize))==NULL)</p>
<p style='line-height:18.0pt'><span
lang=EN-US>{</span></p>
<p style='line-height:18.0pt'><span> </span>MessageBox(hWnd,"Error
alloc memory!","Error Message",</p>
<p style='line-height:
18.0pt'><span lang=EN-US>MB_OK|MB_ICONEXCLAMATION);</span></p>
<p style='line-height:18.0pt'><span>
</span>GlobalUnlock(hSecond);</p>
<p style='line-height:18.0pt'><span>
</span>GlobalFree(hSecond);</p>
<p style='line-height:
18.0pt'><span lang=EN-US>return FALSE;</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>}</span></p>
<p style='line-height:18.0pt'><span> </span> lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData);
</p>
<p style='line-height:18.0pt'><span> </span>lpTempImgData=(LPBITMAPINFOHEADER)LocalLock(hTempImgData);</p>
<p style='line-height:18.0pt'><span> </span>//<span
style='font-family:宋体;"Times New Roman"'>新图缓冲区初始化为</span><span lang=EN-US>255</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>memset(lpTempImgData,(BYTE)255,BufSize);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
"Times New Roman"'>拷贝头信息</span></p>
<p style='line-height:18.0pt'><span> </span>memcpy(lpTempImgData,lpImgData,OffBits);</p>
<p style='line-height:18.0pt'><span> </span>for(y=0;y<bi.biHeight;y++){</p>
<p style='line-height:18.0pt'><span>
</span>pos=(BufSize-LineBytes-y*LineBytes);</p>
<p style='line-height:18.0pt'><span>
</span>//lpPtr<span
style='font-family:宋体;"Times New Roman"'>指向第一幅图，</span><span lang=EN-US>lpSecondPtr</span><span
style='font-family:宋体;"Times New Roman"'>指向第二幅图，</span><span lang=EN-US>lpTempPtr</span><span
style='font-family:宋体;"Times New Roman"'>指向结果图</span></p>
<p style='line-height:18.0pt'><span>
</span>lpPtr=(char *)lpImgData+pos;</p>
<p style='line-height:18.0pt'><span>
</span>lpSecondPtr=(char *)lpSecondImgData+pos;</p>
<p style='line-height:18.0pt'><span>
</span>lpTempPtr=(char *)lpTempImgData+pos;</p>
<p style='line-height:18.0pt'><span>
</span>for(x=0;x<bi.biWidth;x++){</p>
<p style='line-height:18.0pt'><span>
</span>num=(unsigned char)*(lpPtr++);</p>
<p style='line-height:18.0pt'><span>
</span>num-=(unsigned char)*(lpSecondPtr++);</p>
<p style='line-height:18.0pt'><span>
</span>*(lpTempPtr++)=(unsigned char)fabs(num); </p>
<p style='line-height:
18.0pt'><span lang=EN-US>//</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>两者相减取绝对值，存入新图中</span></p>
<p style='line-height:18.0pt'><span>
</span>}</p>
<p style='line-height:18.0pt'><span> </span>}</p>
<p style='line-height:18.0pt'><span> </span> if(hBitmap!=NULL)</p>
<p style='line-height:18.0pt'><span> </span>
DeleteObject(hBitmap);</p>
<p style='line-height:18.0pt'><span> </span>hDc=GetDC(hWnd);</p>
<p style='line-height:18.0pt'><span> </span>//<span
style='font-family:宋体;"Times New Roman"'>创立一个新的位图</span></p>
<p style='line-height:18.0pt'><span> </span>hBitmap=CreateDIBitmap(hDc,(LPBITMAPINFOHEADER)lpTempImgData,</p>
<p style='line-height:
18.0pt'><span lang=EN-US>(LONG)CBM_INIT,</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>(LPSTR)lpTempImgData+</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>sizeof(BITMAPINFOHEADER)+</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>NumColors*sizeof(RGBQUAD),</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>(LPBITMAPINFO)lpTempImgData,</span></p>
<p style='line-height:
18.0pt'><span lang=EN-US>DIB_RGB_COLORS);</span></p>
<p style='line-height:18.0pt'><span
lang=EN-US>hf=_lcreat("c:\\subtract.bmp",0);</span></p>
<p style='line-height:18.0pt'><span> </span>_lwrite(hf,(LPSTR)&bf,sizeof(BITMAPFILEHEADER));
</p>
<p style='line-height:18.0pt'><span> </span>_lwrite(hf,(LPSTR)lpTempImgData,BufSize);</p>
<p style='line-height:18.0pt'><span> </span>_lclose(hf);</p>
<p style='line-height:18.0pt'><span> </span>//<span
style='font-family:宋体;"Times New Roman"'>释放内存和资源</span></p>
<p style='line-height:18.0pt'><span> </span> ReleaseDC(hWnd,hDc);</p>
<p style='line-height:18.0pt'><span> </span>GlobalUnlock(hSecond);</p>
<p style='line-height:18.0pt'><span> </span>GlobalFree(hSecond);</p>
<p style='line-height:18.0pt'><span> </span>LocalUnlock(hTempImgData);</p>
<p style='line-height:18.0pt'><span> </span>LocalFree(hTempImgData);</p>
<p style='line-height:18.0pt'><span> </span>GlobalUnlock(hImgData);</p>
<p style='line-height:18.0pt'><span> </span>return
TRUE;</p>
<p style='line-height:18.0pt'><span lang=EN-US>}</span></p>
<h2> <span
lang=EN-US>8.3</span> <span lang=EN-US> </span><a name="_Toc486331906"></a><a
name="_Toc486332906"></a><a name="_Toc486339015"></a><a name="_Toc454810880"></a><a
name="_Toc454856654"><span><span>模板匹配</span></span></a></h2>
<p style='line-height:18.0pt'><span style='font-family:宋体;
"Times New Roman"'>利用模板匹配可以在一幅图象中找到已知的物体。比如抓拍到了一张射门的照片，要在该照片中找到足球的位置。这时就可以采用模板匹配的方法。所谓模板匹配，其实想法很简单：拿已知的模板</span><span
lang=EN-US>(</span><span style='font-family:宋体;
"Times New Roman"'>在本例中为足球的图象</span><span lang=EN-US>)</span><span
style='font-family:宋体;"Times New Roman"'>，和原图象中同样大小的一块区域去对。</span></p>
<p style='line-height:18.0pt'><span style='font-family:宋体;
"Times New Roman"'>最开始时，模板的左上角点和图象的左上角点是重合的，拿模板和原图象中同样大小的一块区域去对比，然后平移到下一个象素，仍然进行同样的操作，</span><span
lang=EN-US>……</span><span style='font-family:宋体;
"Times New Roman"'>所有的位置都对完后，差别最小的那块就是我们要找的物体。</span></p>
<p style='line-height:18.0pt'><span style='font-family:宋体;
"Times New Roman"'>我们用平方误差之和来衡量原图中的块和模板之间的差别。假设模板的大小为</span><span
lang=EN-US>m×n(</span><span style='font-family:宋体;
"Times New Roman"'>宽</span><span lang=EN-US>×</span><span
style='font-family:宋体;"Times New Roman"'>高</span><span lang=EN-US>)</span><span style='font-family:
宋体;"Times New Roman"'>；图象的大小为</span><span
lang=EN-US>Width×Height</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>。模板中的某点坐标为</span><span
lang=EN-US>(x<sub>0</sub>,y<sub>0</sub>)</span><span style='font-family:宋体;
"Times New Roman"'>，该点的灰度为</span><span
lang=EN-US>U(x<sub>0</sub>,y<sub>0</sub>)</span><span style='font-family:宋体;
"Times New Roman"'>；与之重合的图象中的点坐标为</span><span
lang=EN-US>(X<sub>0</sub>-x<sub>0</sub>,Y<sub>0</sub>-y<sub>0</sub>)</span><span
style='font-family:宋体;"Times New Roman"'>，该点的灰度为</span><span lang=EN-US>V(X<sub>0</sub>-x<sub>0</sub>,Y<sub>0</sub>-y<sub>0</sub>)</span><span
style='font-family:宋体;"Times New Roman"'>。则一次匹配的结果为：</span></p>
<p align=center style='text-align:center;line-height:18.0pt'><span
lang=EN-US><sub> <img width=264 height=48
src="chap08.files/image017.gif" v:shapes="_x0000_i1033"> </sub> </span></p>
<p style='line-height:18.0pt'><span style='font-family:宋体;
"Times New Roman"'>全部图象都匹配后，找到最小的即为结果。可以看到模板匹配的运算量是惊人的。一次匹配都要做</span><span
lang=EN-US>m×n</span><span style='font-family:宋体;
"Times New Roman"'>次减法，</span><span lang=EN-US>m×n</span><span
style='font-family:宋体;"Times New Roman"'>次平方，</span><span lang=EN-US>m×n-1</span><span
style='font-family:宋体;"Times New Roman"'>次加法，整个图象要匹配</span><span lang=EN-US>(Width-m+1)
×(Height-n+1)</span><span
style='font-family:宋体;"Times New Roman"'>次。</span></p>
<p style='line-height:18.0pt'><span style='font-family:宋体;
"Times New Roman"'>源程序不再给出，有兴趣的读者可以自己完成。</span></p>
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