Are both scenarios legal?
- I own a photo, and someone painted a replica (using canvas and paints) and sold prints.
- Someone altered it using Photoshop to look like a painting and sold prints.
Do I need to copyright my pictures to prevent this?
In most countries copyright registration is not required, and copyright is granted by the act of publication. In the US, voluntary registration is available, which is needed to sue for infringement, and gives the copyright holder more possibilities when collecting damages.
As far as the scenarios go, both will include elements of the original work, so they would fall into the category of a derivative work, and depending on the originality (or lack thereof) of the reproduction, may infringe on your copyright. The first is much tougher to prove though, because the original elements of the image are being reproduced in a different medium. In the case of a change using Photoshop, there very well may be enough similarity to prove that infringement has occurred.
You should consult a real lawyer. Do not expect any legal advice over Internet to be meaningful.
My personal opinion is that painted replica is legal and Photoshop alteration is "derivative work" and can be considered legal depending of the copyright of the pictures. Having no specific "written" copyright statement implies some default copyrights and in this case Photoshop alteration is probably not legal.
Your work is always copyrighted, there is no need to register it somewhere. This implied copyright means that you have all the rights to your work. (If you release your work under a certain license it means the same or reduced rights, you can't use a license to increase your rights.)
Whether a copy of your work is legal or not, depends on the sitation. If your photo is unique enough, and the painting isn't, it would be illegal to sell copies.
Shepard Fairey and the Associated Press recently settled a law suit about derivative work. Fairey used an AP photo of Obama to create his famous poster before the 2008 election. You might find some pertinent legal information by reviewing a few articles on this.
Effectively you are asking, when is a derivative work legal?
Two important tests to be applied are
The derivative work "must display some originality of its own. It cannot be a rote, uncreative variation on the earlier, underlying work. The latter work must contain sufficient new expression, over and above that embodied in the earlier work for the latter work to satisfy copyright law’s requirement of originality."
"Transformativeness is a concept used in United States copyright law to describe a characteristic of some derivative works that makes them transcend or place in a new light the underlying works on which they are based."
"The use must be productive and must employ the quoted matter in a different manner or for a different purpose from the original. ...[If] the secondary use adds value to the original--if the quoted matter is used as raw material, transformed in the creation of new information, new aesthetics, new insights and understandings--this is the very type of activity that the fair use doctrine intends to protect for the enrichment of society."
Using your example, where a photo is simply reproduced in another medium, such as oils, it fails both tests:
1) Originality, it is a rote, uncreative variation of the original work.
2) Transformative, it does not add new information, new aesthetics, or new insights and understandings.
All quotes taken from Wikipedia.
For a further discussion see this very interesting article by Professor Stern
L.H.O.O.Q.--Internet-Related Derivative Works
While the caveats about Internet legal advice noted by other answerers apply of course, I think this one is pretty clear: both scenarios involve creation of a derivative work, and if done without permission would be a copyright violation in the USA and many other countries. The fact that the resulting derivative works are sold would generally increase liability.
This may or may not be infringing, depending on the originality of the new work, but in most cases I would say it would be non-infringing. Of course, the owner of the photo can still attempt to sue, but it'd probably be found to be non-infringing especially if the only connection to the original photo is that the artist saw it across the room while painting (and didn't do any cut and paste from it in Photoshop, did not use mechanical means to copy it, didn't lay a stencil over it, etc).
This would certainly be infringing.
Registering copyright on your pictures does not alter what people can and can't do with them, but depending on your country (ie the USA), can affect what you can claim if you successfully sue them in court.
Here's a case of this actually happening with a painting published by the Toronto Star which was found to have been based on a photo by someone else.
Copyright is implied on any works you produce and you don't need to "copyright" your IP. I would suspect that the painting is not illegal (since it is a creation based on your idea, not a copy of your creation itself). The altered photoshopped copy I would be illegal.