捕捉屏幕，处理DDB数据，怎么获取像素数据

捕捉屏幕，处理DDB数据，如何获取像素数据
使用一下代码获取了当前的屏幕图像，想要直接对其像素数据进行处理，
  CRect rect(0, 0, ::GetSystemMetrics(SM_CXSCREEN), ::GetSystemMetrics(SM_CYSCREEN));
  // create a screen and a memory device context
  HDC hDCScreen = ::CreateDC(_T("DISPLAY"), NULL, NULL, NULL);
  HDC hDCMem = ::CreateCompatibleDC(hDCScreen);
  // create a compatible bitmap and select it in the memory DC
  HBITMAP hBitmap = 
  ::CreateCompatibleBitmap(hDCScreen, rect.Width(), rect.Height());
  HBITMAP hBmpOld = (HBITMAP)::SelectObject(hDCMem, hBitmap);

  // bit-blit from screen to memory device context
  // note: CAPTUREBLT flag is required to capture layered windows
  DWORD dwRop = SRCCOPY | CAPTUREBLT;
  BOOL bRet = ::BitBlt(hDCMem, 0, 0, rect.Width(), rect.Height(), 
  hDCScreen, 
  rect.left, rect.top, dwRop);
  CImage m_image。Attach(hBitmap);
但是调用m_image.getBits失败，后查明原因，因为m_image当前是DDB图像，请问各位大侠如何对DBB图像的像素值进行直接处理呢？谢谢！

[解决办法]
CreateDIBSection