question: public static InputStream decompress ( InputStream compressed ) throws FitsException { BufferedInputStream pb = new BufferedInputStream ( compressed , ONE_MEGABYTE ) ; pb . mark ( 2 ) ; int mag1 = - 1 ; int mag2 = - 1 ; try { mag1 = pb . read ( ) ; mag2 = pb . read ( ) ; pb . reset ( ) ; ICompressProvider selectedProvider = selectCompressionProvider ( mag1 , mag2 ) ; if ( selectedProvider != null ) { return selectedProvider . decompress ( pb ) ; } else { return pb ; } } catch ( IOException e ) { throw new FitsException ( "Unable to analyze input stream" , e ) ; } }
target:  This method decompresses a compressed input stream. The decompression method is selected automatically based upon the first two bytes read.