I've not used any of the InterMedia packages; I would guess that they're just more-or-less straight-forward stored procedure calls.
Oracle has lot of information on-line:
JDBC samples, many of which are complete working programs
http://www.oracle.com/technology/sample_code/tech/java/sqlj_jdbc/index.html
JDBC Developers Guide and Reference
http://download-east.oracle.com/docs/cd/B19306_01/java.102/b14355/toc.htm
Some other JDBC links and the driver compatability chart...
http://www.oracle.com/technology/tech/java/sqlj_jdbc/index.html
Also, you can download the JavaDocs for Oracle's extenstions to JDBC from the same place the drivers are available:
http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/index.html
If you don't want/need to use Intermedia, the JDBC examples include storage and retriaval of an image as a BLOB, in the LOB example.