Finding if value is null or not in binary data type field

[iwin]

Hi all,
I am trying to find if the value of a field which is defined as binary data type as column defination is null or not. I tried doing isnull , isnotnull, length=0 or trim(colname)='' in transformer after the join Stage but none is working.
Please let me know if u any idea how to handle null in this situation.

Thanks.