HDIB BitmapToDIB(HBITMAP hBitmap, HPALETTE hPal)
{
    BITMAP              bm;         // bitmap structure
    BITMAPINFOHEADER    bi;         // bitmap header
    LPBITMAPINFOHEADER  lpbi;       // pointer to BITMAPINFOHEADER
    DWORD               dwLen;      // size of memory block
    HANDLE              hDIB, h;    // handle to DIB, temp handle
    HDC                 hDC;        // handle to DC
    WORD                biBits;     // bits per pixel

    // check if bitmap handle is valid

    if (!hBitmap)
        return NULL;

    // fill in BITMAP structure, return NULL if it didn't work

    if (!GetObject(hBitmap, sizeof(bm), (LPSTR)&bm))
        return NULL;

    // if no palette is specified, use default palette

    if (hPal == NULL)
        hPal = (HPALETTE)GetStockObject(DEFAULT_PALETTE);

    // calculate bits per pixel

    biBits = bm.bmPlanes * bm.bmBitsPixel;

    // make sure bits per pixel is valid

    if (biBits <= 1)
        biBits = 1;
    else if (biBits <= 4)
        biBits = 4;
    else if (biBits <= 8)
        biBits = 8;
    else // if greater than 8-bit, force to 24-bit
        biBits = 24;

    // initialize BITMAPINFOHEADER

    bi.biSize = sizeof(BITMAPINFOHEADER);
    bi.biWidth = bm.bmWidth;
    bi.biHeight = bm.bmHeight;
    bi.biPlanes = 1;
    bi.biBitCount = biBits;
    bi.biCompression = BI_RGB;
    bi.biSizeImage = 0;
    bi.biXPelsPerMeter = 0;
    bi.biYPelsPerMeter = 0;
    bi.biClrUsed = 0;
    bi.biClrImportant = 0;

    // calculate size of memory block required to store BITMAPINFO

    dwLen = bi.biSize + PaletteSize((LPSTR)&bi);

    // get a DC

    hDC = GetDC(NULL);

    // select and realize our palette

    hPal = SelectPalette(hDC, hPal, FALSE);
    RealizePalette(hDC);

    // alloc memory block to store our bitmap

    hDIB = GlobalAlloc(GHND, dwLen);

    // if we couldn't get memory block

    if (!hDIB)
    {
      // clean up and return NULL

      SelectPalette(hDC, hPal, TRUE);
      RealizePalette(hDC);
      ReleaseDC(NULL, hDC);
      return NULL;
    }

    // lock memory and get pointer to it

    lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDIB);

    /// use our bitmap info. to fill BITMAPINFOHEADER

    *lpbi = bi;

    // call GetDIBits with a NULL lpBits param, so it will calculate the
    // biSizeImage field for us    

    GetDIBits(hDC, hBitmap, 0, (UINT)bi.biHeight, NULL, (LPBITMAPINFO)lpbi,
        DIB_RGB_COLORS);

    // get the info. returned by GetDIBits and unlock memory block

    bi = *lpbi;
    GlobalUnlock(hDIB);

    // if the driver did not fill in the biSizeImage field, make one up 
    if (bi.biSizeImage == 0)
        bi.biSizeImage = WIDTHBYTES((DWORD)bm.bmWidth * biBits) * bm.bmHeight;

    // realloc the buffer big enough to hold all the bits

    dwLen = bi.biSize + PaletteSize((LPSTR)&bi) + bi.biSizeImage;

    if (h = GlobalReAlloc(hDIB, dwLen, 0))
        hDIB = h;
    else
    {
        // clean up and return NULL

        GlobalFree(hDIB);
        hDIB = NULL;
        SelectPalette(hDC, hPal, TRUE);
        RealizePalette(hDC);
        ReleaseDC(NULL, hDC);
        return NULL;
    }

    // lock memory block and get pointer to it */

    lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDIB);

    // call GetDIBits with a NON-NULL lpBits param, and actualy get the
    // bits this time

    if (GetDIBits(hDC, hBitmap, 0, (UINT)bi.biHeight, (LPSTR)lpbi +
            (WORD)lpbi->biSize + PaletteSize((LPSTR)lpbi), (LPBITMAPINFO)lpbi,
            DIB_RGB_COLORS) == 0)
    {
        // clean up and return NULL

        GlobalUnlock(hDIB);
        hDIB = NULL;
        SelectPalette(hDC, hPal, TRUE);
        RealizePalette(hDC);
        ReleaseDC(NULL, hDC);
        return NULL;
    }

    bi = *lpbi;

    // clean up 
    GlobalUnlock(hDIB);
    SelectPalette(hDC, hPal, TRUE);
    RealizePalette(hDC);
    ReleaseDC(NULL, hDC);
    // return handle to the DIB
    return hDIB;
}