biWidth wrong in tagBITMAPINFOHEADER when using twain

bool CScanDialog::PDFAddPicturePage(HDIB hDIB)
{
  HPDF_Page  page;
  HPDF_Image image;
 
  BYTE * BGRimage;
  BGRimage = (BYTE *) GlobalLock(hDIB);
 
  /*
    typedef struct tagBITMAPINFOHEADER{
      DWORD  biSize; 
      LONG   biWidth; 
      LONG   biHeight; 
      WORD   biPlanes; 
      WORD   biBitCount; 
      DWORD  biCompression; 
      DWORD  biSizeImage; 
      LONG   biXPelsPerMeter; 
      LONG   biYPelsPerMeter; 
      DWORD  biClrUsed; 
      DWORD  biClrImportant; 
    } BITMAPINFOHEADER, *PBITMAPINFOHEADER; 
  */
 
  long img_width    = * (BGRimage + 1 * sizeof(DWORD) + 3); img_width *= 0x100;
       img_width   += * (BGRimage + 1 * sizeof(DWORD) + 2); img_width *= 0x100;
       img_width   += * (BGRimage + 1 * sizeof(DWORD) + 1); img_width *= 0x100;
       img_width   += * (BGRimage + 1 * sizeof(DWORD)    );
  long img_height   = * (BGRimage + 1 * sizeof(DWORD) + 1 * sizeof(long) +3);img_height *= 0x100;
       img_height  += * (BGRimage + 1 * sizeof(DWORD) + 1 * sizeof(long) +2);img_height *= 0x100;
       img_height  += * (BGRimage + 1 * sizeof(DWORD) + 1 * sizeof(long) +1);img_height *= 0x100;
       img_height  += * (BGRimage + 1 * sizeof(DWORD) + 1 * sizeof(long) +0);
  DWORD img_header_length  = * (BGRimage +1); img_header_length *= 0x100;
        img_header_length += * (BGRimage);
 
  BGRimage += img_header_length; // Offset of the header
  BGRimage += (0xFF * 4);        // Offset of the color table
  /*Here some  code that writes the image to a pdf file*/
}