''' <summary>
''' Renders all pages of PPTX document and saves rendered images to PNG files.
''' </summary>
''' <param name="filename">A name of PPTX file.</param>
Public Shared Sub RenderAndSavePptxPages(filename As String)
    ' open PPTX document
    Using pptxDocument As New Vintasoft.Imaging.Office.OpenXml.Pptx.PptxDocument(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read)
        ' for each PPTX page
        For i As Integer = 0 To pptxDocument.Pages.Count - 1
            ' render PPTX page
            Using renderedPage As Vintasoft.Imaging.VintasoftImage = pptxDocument.Pages(i).Render()
                ' save rendered image to a PNG file
                renderedPage.Save(String.Format("page{0}.png", i))
            End Using
        Next
    End Using
End Sub

/// <summary>
/// Renders all pages of PPTX document and saves rendered images to PNG files.
/// </summary>
/// <param name="filename">A name of PPTX file.</param>
public static void RenderAndSavePptxPages(string filename)
{
    // open PPTX document
    using (Vintasoft.Imaging.Office.OpenXml.Pptx.PptxDocument pptxDocument =
        new Vintasoft.Imaging.Office.OpenXml.Pptx.PptxDocument(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read))
    {
        // for each PPTX page
        for (int i = 0; i < pptxDocument.Pages.Count; i++)
        {
            // render PPTX page
            using (Vintasoft.Imaging.VintasoftImage renderedPage = pptxDocument.Pages[i].Render())
            {
                // save rendered image to a PNG file
                renderedPage.Save(string.Format("page{0}.png", i));
            }
        }
    }
}