Use Open Graph to share stories with (large) user generated action photos.
The documentation is here: https://developers.facebook.com/docs/opengraph/usergeneratedphotos/
Something like this will work, in conjunction with an Open Graph action post.
https://graph.facebook.com/me/yournamespace:cook?
recipe=http://www.yourdomain.com/pizza.html&
image[0][url]=http://www.yourdomain.com/images/my_camera_pizza_pic.jpg&
image[0][user_generated]=true
You can also post a photo to a user's albums using the https://developers.facebook.com/docs/reference/api/photo/ API
Which you choose to use partly depends on the use case you have in mind.