As far as being able to receive statutory damages, it is a matter of when you register. If you don't register in a timely manner to be able to receive statutory damages, and want to pursue a lawsuit to obtain actual damages, you still must register the images before proceeding with a lawsuit.
This is an accurate statement of the U.S. requirement for enforcing a copyright in court
except for works that were created in another country that is a signatory to the Berne Convention.
So while a copyright for work created in the United States exists without the requirement for "any formality," as in other Berne signatory countries, judicial enforcement is only available after the work has been registered. In other words, if a U.S. copyright holder discovers a presumptive infringement, the copyright must be registered prior to taking legal action to recover damages.
(There is a disagreement among the U.S. federal appellate courts about a particular aspect of the registration requirement that is not relevant here.)
If the work was created in another country, it's a little more complicated.
In the United States, treaties are typically "self-executing"—upon ratification, they become judicially enforceable as U.S. federal law. However, when the United States belatedly joined the Berne Convention, it did so with an important qualification: the international copyright provisions would require explicit implementing legislation, which Congress enacted in 1988.
I think that's what makes the U.S. law confusing. We follow the Berne rules with respect to copyright
creation, but not with respect to copyright
enforcement.
Except for works created in other Berne signatory countries. The U.S. implementing legislation permits their owners to sue for "actual damages"—for example, lost revenue—without having to go through the formality of registration. However, if they register within a specified time period ("not later than the earlier of 3 months after the first publication of the work or 1 month after the copyright owner has learned of the infringement"), they also can collect additional damages specified in the U.S. copyright law.
To summarize:
- Copyrights for works created in the United States cannot be enforced without registration.
- Copyrights for works created in other Berne signatory countries can be enforced in the United States without registration with respect to actual damages.
- Copyrights for works created in other Berne signatory countries are eligible for additional U.S. statutory remedies if they are registered in a timely manner.
In case it isn't obvious, the policy behind the U.S. registration requirement is to create a presumption of a valid copyright before an infringement claim winds up in court. If the validity of the copyright is challenged in a lawsuit, the defendant has the burden of proving its invalidity.