chap05.htm

数字图像处理入门. 一位图像处理高手写的书. 从图像处理的最基础开始,然后慢慢以一些例子做说明,进入图像处理的更高阶段.学习图像处理不可多得的比较朴实的书

宋体;&quot;Times New Roman&quot;'>章中提到了</span><span
lang=EN-US>YUV</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>的颜色表示方法，在这种表示方法中，</span><span
lang=EN-US>Y</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>分量的物理含义就是亮度，它含了灰度图</span><span
lang=EN-US>(grayscale)</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>的所有信息，只用</span><span
lang=EN-US>Y</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>分量就完全能够表示出一幅灰度图来。</span><span
lang=EN-US>YUV</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>和</span><span lang=EN-US>RGB</span><span
style='font-family:宋体;"Times New Roman"'>之间有着如下的对应关系：</span></p>
  <p align=center style='text-align:center;line-height:18.0pt'><span
lang=EN-US><sub> <img width=352 height=77
src="chap05.files/image006.gif"  v:shapes="_x0000_i1027"> </sub> </span></p>
  <p style='line-height:18.0pt'><span
style='font-family:宋体;"Times New Roman"'>我们利用上式，根据</span><span lang=EN-US>R</span><span
style='font-family:宋体;"Times New Roman"'>、</span><span lang=EN-US>G</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>、</span><span
lang=EN-US>B</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>的值求出</span><span lang=EN-US>Y</span><span
style='font-family:宋体;"Times New Roman"'>值后，将</span><span lang=EN-US>R</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>、</span><span
lang=EN-US>G</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>、</span><span lang=EN-US>B</span><span
style='font-family:宋体;"Times New Roman"'>值都赋值成</span><span lang=EN-US>Y</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>，就能表示出灰度图来，这就是彩色图转灰度图的原理。</span></p>
  <p style='line-height:18.0pt'><span
style='font-family:宋体;"Times New Roman"'>先看看真彩图。我们知道真彩图不带调色板，每个象素用</span><span lang=EN-US>3</span><span
style='font-family:宋体;"Times New Roman"'>个字节，表示</span><span lang=EN-US>R</span><span
style='font-family:宋体;"Times New Roman"'>、</span><span lang=EN-US>G</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>、</span><span
lang=EN-US>B</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>三个分量。所以处理很简单，根据</span><span
lang=EN-US>R</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>、</span><span lang=EN-US>G</span><span
style='font-family:宋体;"Times New Roman"'>、</span><span lang=EN-US>B</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>的值求出</span><span
lang=EN-US>Y</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>值后，将</span><span lang=EN-US>R</span><span
style='font-family:宋体;"Times New Roman"'>、</span><span lang=EN-US>G</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>、</span><span
lang=EN-US>B</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>值都赋值成</span><span lang=EN-US>Y</span><span
style='font-family:宋体;"Times New Roman"'>，写入新图即可。</span></p>
  <p style='line-height:18.0pt'><span
style='font-family:宋体;"Times New Roman"'>再来看看带调色板的彩色图，我们知道位图中的数据只是对应调色板中的一个索引值，我们只需要将调色板中的彩色变成灰度，形成新调色板，而位图数据不用动，就可以了。</span></p>
  <p style='line-height:18.0pt'><span
style='font-family:宋体;"Times New Roman"'>下面的程序实现了彩色图到灰度图的转换，注意其中真彩图和调色板位图处理时的差别。</span></p>
  <p style='line-height:18.0pt'><span lang=EN-US>BOOL ColortoGrayScale(HWND hWnd)</span></p>  
  <p style='line-height:18.0pt'><span lang=EN-US>{</span></p>
  <p style='line-height:18.0pt'>DWORD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SrcOffBits,SrcBufSize,DstBufSize,DstLineBytes;</p>  
  <p style='line-height:18.0pt'>LPBITMAPINFOHEADER&nbsp;&nbsp;&nbsp; lpImgData;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>LPSTR&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp; lpPtr;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>HLOCAL&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hTempImgData;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>LPBITMAPINFOHEADER&nbsp;&nbsp;&nbsp;   
    lpTempImgData;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>LPSTR&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp; lpTempPtr;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>HDC&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp; hDc;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>HFILE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp; hf;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>LONG&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp; x,y;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>BITMAPFILEHEADER&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; DstBf;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>BITMAPINFOHEADER   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; DstBi;</p>  
  <p style='line-height:18.0pt'>LOGPALETTE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp; *pPal;</p>  
  <p style='line-height:18.0pt'>HPALETTE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    hPrevPalette; </p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>HLOCAL&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hPal;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DWORD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; NewNumColors;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>WORD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    NewBitCount;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>float&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Y;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DWORD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   
    &nbsp;&nbsp; i;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>unsigned   
    char&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Red,Green,Blue,Gray;</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>NewNumColors=NumColors;   
    //NewNumColors<span style='font-family:宋体;
&quot;Times New Roman&quot;'>为新图的颜色数</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>NewBitCount=bi.biBitCount;&nbsp;   
    //NewBitCount<span
style='font-family:宋体;"Times New Roman"'>为新图的颜色位数</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>if(NumColors==0)   
    //<span style='font-family:宋体;
&quot;Times New Roman&quot;'>真彩图</span></p>
  <p style='line-height:18.0pt'><span
lang=EN-US>{</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
    </span>NewNumColors=256;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
    </span>NewBitCount=8;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>}</p>
  <p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>由于颜色位数有可能发生了改变，所以要重新计算每行占用的字节数以及</span></p>
  <p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;
&quot;Times New Roman&quot;'>新图的缓冲区大小</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstLineBytes=(DWORD)WIDTHBYTES(bi.biWidth*NewBitCount);</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstBufSize=(DWORD)(sizeof(BITMAPINFOHEADER)+NewNumColors*</p>
  <p style='line-height:
18.0pt'><span lang=EN-US>sizeof(RGBQUAD)+(DWORD)DstLineBytes*bi.biHeight);</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span><a name=b1></a>//DstBf<span  
style='font-family:宋体;"Times New Roman"'>和</span><span lang=EN-US>DstBi</span><span style='font-family:
宋体;&quot;Times New Roman&quot;'>为新的</span><span
lang=EN-US>BITMAPFILEHEADER</span><span style='font-family:宋体;"Times New Roman";"Times New Roman"'>和</span><span
lang=EN-US>BITMAPINFOHEADER</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>//<span
style='font-family:宋体;"Times New Roman"'>拷贝原来的头信息</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>memcpy((char   
    *)&amp;DstBf,(char *)&amp;bf,sizeof(BITMAPFILEHEADER));</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>memcpy((char   
    *)&amp;DstBi,(char *)&amp;bi,sizeof(BITMAPINFOHEADER));</p>  
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>//<span
style='font-family:宋体;"Times New Roman"'>做必要的改变</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstBf.bfSize=DstBufSize+sizeof(BITMAPFILEHEADER);</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstBf.bfOffBits=(DWORD)(NewNumColors*sizeof(RGBQUAD)+</p>
  <p style='line-height:
18.0pt'><span lang=EN-US>sizeof(BITMAPFILEHEADER)+</span></p>
  <p style='line-height:
18.0pt'><span lang=EN-US>sizeof(BITMAPINFOHEADER));</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstBi.biClrUsed=0;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>DstBi.biBitCount=NewBitCount;</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>//<span
style='font-family:宋体;"Times New Roman"'>原图的缓冲区的大小</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>SrcOffBits=bf.bfOffBits-   
    sizeof(BITMAPFILEHEADER);</p>
  <p style='line-height:18.0pt'><span
lang=EN-US>SrcBufSize=SrcOffBits+bi.biHeight*LineBytes;</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>if((hTempImgData=LocalAlloc(LHND,DstBufSize))==NULL)</p>
  <p style='line-height:18.0pt'><span
lang=EN-US>{</span></p>
  <p style='line-height:
18.0pt'><span lang=EN-US>MessageBox(hWnd,&quot;Error alloc memory!&quot;,&quot;Error 
    Message&quot;,MB_OK|</span></p>
  <p style='line-height:
18.0pt'><span lang=EN-US>MB_ICONEXCLAMATION);</span></p>
  <p style='line-height:
18.0pt'><span lang=EN-US>return FALSE;</span></p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp; </span>}</p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp; </span>&nbsp; lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData);&nbsp;&nbsp;&nbsp;   
  </p>
  <p style='line-height:18.0pt'><span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>lpTempImgData=(LPBITMAPINFOHEADER)LocalLock(hTempImgData);</p>
  <p style='line-height:18.0pt'><span
lang=EN-US>//</span><span style='font-family:宋体;