You can access sqlite database tables, and BLOBs, using the Python interface:
>> dbFileName = 'myDatabase.db';
>> tableName = 'myTable'
% Say the field name is data and there is an id field whos value we're after is 300
>> sql = py.importlib.import_module('sqlite3');
>> conn = sql.connect(dbFileName);
>> cur = conn.cursor()
>> query = 'SELECT data FROM myTable WHERE id=300';
>> cur.execute(query);
>> res = cur.fetchone();
% The above returns a Python tuple containing the id and the blob. This gets you the data:
>> data = res{2}.uint8;