I am attaching the code to export all the slides from a Power Point to Images

string ExportLocation = "C:\\Sample";
Microsoft.Office.Interop.PowerPoint.Application ppApp = new Microsoft.Office.Interop.PowerPoint.Application();
ppApp.Visible = MsoTriState.msoTrue;
ppApp.WindowState = PpWindowState.ppWindowMinimized;
Microsoft.Office.Interop.PowerPoint.Presentations oPresSet = ppApp.Presentations;
Microsoft.Office.Interop.PowerPoint._Presentation oPres = oPresSet.Open("C:\\ScreenShots.ppt",
            MsoTriState.msoFalse, MsoTriState.msoFalse,
            MsoTriState.msoFalse);
ppApp.ShowWindowsInTaskbar = MsoTriState.msoFalse;	//Hiding the application; But it will be displayed always
try
{
    Slides objSlides = oPres.Slides;	//Getting all the slides
    for (int i = 1; i < objSlides.Count - 1; i++)
    {
        string file = Path.Combine(ExportLocation, string.Format("{0}.{1}", objSlides[i].Name, "jpg"));
        oPres.Slides[i].Export(file, "jpg", 800, 600);
    }
}
finally
{
    ppApp.Quit();	//Closing the Powerpoint application. Sometimes it won't work too.
}

Thanks to ArunKumar, for providing the code snippet.