Please study my answer in your earlier thread docx-java-f6/getting-images-from-docx-t1502.html ; the principles are the same.
You need to get the relID etc.
Once you have looked into it, feel free to post again to that earlier thread, including the XML for the pic object, and the code you have written.
I'm going to delete this thread, so it doesn't clutter up other people's search results.