将各种格式的图像转换为灰度图像

来源：互联网发布：西安明朝万达 JAVA 编辑：程序博客网时间：2024/06/06 21:39

接着上一篇的程序。下面的一个功能是利用FreeImage将各种格式的图像转换为灰度图像。

方法一：自己写转换函数；

下面的代码就是将各种编码格式的图像转化为灰度图像的处理函数：

    FIBITMAP* CGenricImageTransformerView::TransformToGrayscale(FIBITMAP *dib)      {          const int nBitCounts = 8;          int nBpp = FreeImage_GetBPP(dib);          BYTE* imgData = FreeImage_GetBits(dib);          int width = FreeImage_GetWidth(dib);          int height = FreeImage_GetHeight(dib);          FIBITMAP* fiBmp = FreeImage_Allocate(width,height,nBitCounts);          RGBQUAD* pRGBTable = FreeImage_GetPalette(fiBmp);          //创建灰度索引调色板          for (int i = 0;i<256;i++)          {              pRGBTable[i].rgbBlue = i;              pRGBTable[i].rgbGreen = i;              pRGBTable[i].rgbRed = i;          }          BYTE nIntensity;          int j,k;          switch(nBpp)          {          case 32:        //32位图（带alpha通道）转换为8位灰度图              for(j=0;j<height;j++)              {                  for(k=0;k<4*width;k++)                  {                      nIntensity = (BYTE)(0.299*imgData[j*4*width+k]+                          0.587*imgData[j*4*width+k+1]+0.114*imgData[j*4*width+k+2]);                      if(k%4)                          FreeImage_SetPixelIndex(fiBmp,k/4,j,&nIntensity);                  }              }              return fiBmp;          break;          case 24:        //24位图像转为8位灰度图                for(j=0;j<height;j++)              {                  for(k=0;k<3*width;k++)                  {                      nIntensity = (BYTE)(0.299*imgData[j*3*width+k]+                              0.587*imgData[j*3*width+k+1]+0.114*imgData[j*3*width+k+2]);                      if(k%3)                          FreeImage_SetPixelIndex(fiBmp,k/3,j,&nIntensity);                  }              }              return fiBmp;          break;          case 8:     //8位伪彩色转为8位灰度图              for(j=0;j<height;j++)              {                  for(k=0;k<width;k++)                  {                      FreeImage_GetPixelIndex(dib,k,j,&nIntensity);                      RGBQUAD* ptrRGB = FreeImage_GetPalette(dib);                      nIntensity = (BYTE)(0.299*ptrRGB[nIntensity].rgbRed+                          0.587*ptrRGB[nIntensity].rgbGreen+0.114*ptrRGB[nIntensity].rgbBlue);                      FreeImage_SetPixelIndex(fiBmp,k,j,&nIntensity);                  }              }              return fiBmp;          break;          default:              break;          }          return NULL;

在菜单栏中新建一个菜单项，设置标签为：转换为灰度图像，并添加命令处理函数：

    void CGenricImageTransformerView::OnTransformToGrayscale()       {          // TODO: Add your command handler code here          FIBITMAP* fiBitmap = TransformToGrayscale(dib);          CFileDialog fileDlg(FALSE,".bmp","img.*",OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,                              "bmp(*.bmp)|*.bmp|jpg(*.jpg)|*.jpg|/                              tif(*.tif)|*.tif|png(*.png)|*.png|/                              gif(*.gif)|*.gif|Any(*.*)|*.*||",                               NULL);                    if(IDOK == fileDlg.DoModal())          {              CString filename = fileDlg.GetFileName();              BOOL bSuccess = GenericWriter(fiBitmap,filename);              if(!bSuccess)                  MessageBox("Not support that type!");

方法二：直接调用FreeImage库中已经定义好的转换函数：

   void CGenricImageTransformerView::OnTransformToGrayscale()       {          // TODO: Add your command handler code here          FIBITMAP* fiBitmap =FreeImage_ConvertToGrayscale(dib);//这里调用FreeImage库中的转换为灰度的函数          CFileDialog fileDlg(FALSE,".bmp","img.*",OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,                              "bmp(*.bmp)|*.bmp|jpg(*.jpg)|*.jpg|/                              tif(*.tif)|*.tif|png(*.png)|*.png|/                              gif(*.gif)|*.gif|Any(*.*)|*.*||",                               NULL);                    if(IDOK == fileDlg.DoModal())          {              CString filename = fileDlg.GetFileName();              BOOL bSuccess = GenericWriter(fiBitmap,filename);              if(!bSuccess)                  MessageBox("Not support that type!");          }                }

用起来也特别方便，除此之外，FreeImage提供了其他的转换函数，可以转换为4位、8位、16位、24位、32位等图像类型。

原文地址：http://blog.csdn.net/summersolstice/article/details/5161859

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