I'm a bit rusty with this but I don't think you can just copy over the value from one table to another. I think you will have to stream the image out of one table and then put that stream of binary data back in the other table.
I assume you have code to upload the image to the database and read the image in from the database... In this case, you will be combining them both in reverse i.e. read the image from the database and upload it to the other table.