static ImageDecoder( )
{
// register PNM file format
IImageDecoder decoder = new PNMCodec( );
RegisterDecoder( "pbm", decoder );
RegisterDecoder( "pgm", decoder );
RegisterDecoder( "pnm", decoder );
RegisterDecoder( "ppm", decoder );
// register FITS file format
decoder = new FITSCodec( );
RegisterDecoder( "fit", decoder );
RegisterDecoder( "fits", decoder );
}