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);
}