Your requirement seems pretty clear, since you need to fetch Images from Product your association needs to be Product->Image only i.e. uni directional.
If you envision an additional scenario in which you fetch all the images, and want to show the Product for each image you would want to make your association bidirectional.
Please remember that if you make an association bi-directional, you will need to pick a owning side. In your schema I don't see any Foreign keys, however form your problem description I would think that IMAGE would have PRODUCT_ID to point to the product. In this case make Image the owner of the association.