怎么获取ppt的分辨率

Question

  Presentations objPresSet = objApp.Presentations;
                    _Presentation objPres = objPresSet.Open("G:\\123.ppt", Microsoft.Office.Core.MsoTriState.msoTrue, Microsoft.Office.Core.MsoTriState.msoTrue, Microsoft.Office.Core.MsoTriState.msoFalse);
                    Slides objSlides = objPres.Slides;
                    int i = objSlides.Count;//ppt页数                    float w = objPres.Application.Width;
                    float h = objPres.Application.Height;
                    float wd = objSlides.Application.Width;
                    float hg = objSlides.Application.Height;
哪个属性是ppt的分辨率啊？