/**
 \defgroup ITKIOPNG Module ITKIOPNG 
 This module contains an ImageIO class for reading and writing
files in the Portable Network Graphics (PNG) format. 
 \par Dependencies:
 \li \ref ITKIOImageBase 
 \li \ref ITKPNG 
 \dot 
 graph "ITKIOPNG" { 
 "ITKIOPNG" -- "ITKIOImageBase"; 
 "ITKIOPNG" -- "ITKPNG"; 
 } 
 \enddot 
 */