ok

so just say we have 3 sequential letters
abc

in binary radix 2 that is : 110000111000101100011
in radix 256 (ascii) that is: 96, 97, 98
in radix 256 symbols it is: abc

that means to further compress the file, you would have to come up with symbols for every 2 bytes of information ie 65536 unique different symbols which would reduce the number of characters only by half.