George,

First, stop bugging me :-)

I presume that because your going to be using the StretchBlt() API call that your dealing with DDB's. If you blit and scale into a new, compatible memory DC then you can get at the DDB pixel array directly using the GetBitmapBits API call.

void DDBPixelBits(HWND hWnd, HBITMAP hBmp)
{
int nSize;

   nSize = GetBitmapBits(hBmp, 0, NULL);
   BYTE *pPixelArray = new BYTE[nSize];

   if (pPixelArray)
   {
      GetBitmapBits(hBmp, nSize, pPixelArray);
      delete [] pBuffer;
   }
}

You may still have to bugger about a bit with the conversion but getting at the pixel array should give you most of the information required.