question: protected void readHeader ( ) { String id = "" ; for ( int i = 0 ; i < 6 ; i ++ ) { id += ( char ) read ( ) ; } if ( ! id . startsWith ( "GIF" ) ) { status = STATUS_FORMAT_ERROR ; return ; } readLSD ( ) ; if ( gctFlag && ! err ( ) ) { gct = readColorTable ( gctSize ) ; bgColor = gct [ bgIndex ] ; } }
target:  Reads GIF file header information.