how to read blob as binary value in SAP

I tried the official demo demo_db_writer and demo_db_reader for writing and reading LOB. I save a image to the table and read it .It worked but I have a question, in other DB when I query the blob field it contain lots of ? or ! like characters. But in HANA blob field all characters are 0-9 and A-Z. So is this because some special coding method of HANA? Thx.