edge detection based on sobel operator in MFC

void CChildView::OnEdge() // edge detection based on Sobel operators
{

 {
 int operx[3][3]={-1,0,1,-2,0,2,-1,0,1};//Sobel operators
 int opery[3][3]={1,2,1,0,0,0,-1,-2,-1};//Sobel operators
 int i,j;
 int p=0;
 int smx=0,smy=0;
 //CImage img_tem;
 //img_tem.Create(img_width,img_hight,24,0);
 for(i=0;i<img_hight;i++)
 {
  for(j=0;j<img_width;j++)
  {

   COLORREF cf = MyRGB(0,0,0);
   img_final.SetPixel(j,i,cf); //img_final is a member of this class, this is to reset it to zeros
         
  }
 }



 for(i=0;i<img_hight-2;i++)
 {
  for(j=0;j<img_width-2;j++)
  {

            smx=0;
   smy=0;
   for (int m=0; m<3; m++)
   {
      for (int n=0; n<3; n++)
      {   
      COLORREF rgb=img_new.GetPixel(j+n,i+m);
         int p=MyGetRValue(rgb);
                  smx=smx+p*operx[m][n];
                  smy=smy+p*opery[m][n];
      }
   }

   float G=smx*smx+smy*smy;
   int GD=(int)sqrt(G);
            
   if(GD>100) // threshold to determine whether it is an edge
   {
         COLORREF cf = MyRGB(255,255,255);
         img_final.SetPixel(j+1,i+1,cf);
 
   }

  }
 }
  
   Invalidate(); //call the OnPaint to show the result


}

basic image processing in MFC

Everybody knows that MFC+OpenCV is very convenient for image processing. But how about only using MFC? Most of the operation for image processing is based on bitmap in previous MFC version, say VC++6.0.

In VS2008, there is already CImage class, which could greatly facilitate the image processing.
 (1) get basic info of one image

  #include <atlimage.h>

  ...

  CImage img; //image object

  img.Load(FilePathName); // load a local image
  img_hight=img.GetHeight();//get hight
  img_width=img.GetWidth();//get width
  img_bits=img.GetBPP();//get bit counts for each pixel, say 8,24,32...

  COLORREF rgb=img.GetPixel(10,10);// get the pixel color

  



  CImage img_new; //another image object

  img_new.Create(img_width, img_hight, 24, 0);//create a image with the same size

  img.SetPixel(10,10,rgb);// set the pixel color

(2) get the r,g,b value from the COLORREF value:

#define MyGetRValue(rgb) ((BYTE)(rgb))
#define MyGetGValue(rgb) ((BYTE)(((WORD)(rgb)) >> 8))
#define MyGetBValue(rgb) ((BYTE)((rgb)>>16)) 



 COLORREF rgb=img.GetPixel(j,i);
 int r = MyGetRValue(rgb);

 int g=MyGetGValue(rgb);

 int b=MyGetBValue(rgb);

(3) convert the 24bit color image into gray image:

 #define MyRGB(r,g,b) ((COLORREF)(((BYTE)(r)|((WORD)((BYTE)(g))<<8))|(((DWORD)(BYTE)(b))<<16)))



 BYTE cl = (BYTE)(0.299 * r + 0.587 * g + 0.114 * b);
 int clr=(int)cl;
 COLORREF cf = MyRGB(clr,clr,clr);
  img_gray.SetPixel(j,i,cf);