Portable Network Graphic (.png) is a type of raster image file format that use loseless compression. This file format was created as a replacement of Graphics Interchange Format (GIF) and has no copyright limitations.
Learn more about this file format here
GroupDocs.Viewer (in GroupDocs.Viewer.dll) Version: 20.7
public static readonly FileType PNG
Public Shared ReadOnly PNG As FileType
static initonly FileType^ PNG