title: Accordance between pixel and mm
body: <p>I'm doing:</p>
  
  <pre><code>        PhysicalParameters()
      {
          IntPtr DeskTopHWND = GetDesktopWindow();
          IntPtr HDC = GetDC(DeskTopHWND);
          int mmX = GetDeviceCaps(HDC, HORZSIZE);
          int mmY = GetDeviceCaps(HDC, VERTSIZE);
          int pxX = GetDeviceCaps(HDC, HORZRES);
          int pxY = GetDeviceCaps(HDC, VERTRES);
          ReleaseDC(DeskTopHWND, HDC);
          double CoeffPIX_MM_X = 1.0 * mmX / pxX;
          double CoeffPIX_MM_Y = 1.0 * mmY / pxY;
      }
  </code></pre>
  
  <p>The result for both is 0.25</p>
  
  <p>But what I see (MS Word' WysiWyg ) it should be about 0.27</p>
  
  <p>Please, explain the subject.</p>