I am disinclined to treat this as simply one to 'chalk up to experience' simply because of CC licensing.
No the cafe owner needs to display a credit, though I'd also be willing to bet the cafe own has brought the images from someone/somewhere
which could also raise an interesting question on liability
In the terms of the CC licence cited, there is no ambiguity: the licence requires attribution of the author of the work, and that for any re-use of the image, the terms of the CC licence must be made clear to others.
If the owner of the bar was unaware of the terms of the licence, then, legally, they must assume that normal copyright terms apply.
If they were misled by the person that supplied the image to them, then it is a contractual matter between the restaurant and the person that supplied the image to them.
but if he doesn't display a credit then the license is broken.
Quite. CC is a system of licensing built within copyright law, not an alternative to copyright law.
If I licence (not-CC) one of my photographs to a company for use in a company report with a print run of 2,500 copies, and subsequently discover that they have used it in an advertising campaign, they have breached the terms of their licence and I would be entitled to take action against them for infringement of my copyright.
There is no difference in principle in this case. The terms of the OP's licence have been breached (by not providing proper attribution on the copies displayed in the restaurant). At this point the restaurant holds no legal licence to use the work* and the OP is entitled to seek redress for the infringement.
While not in the UK courts, there is precedent in a similar case in Germany.
http://wiki.creativecommons.org/Gerlach_vs._DVU
creativecommons.org has a listing of other case law relating to the use of CC licences:
http://wiki.creativecommons.org/Case_Law
There are other, similar cases (mostly also in Germany) where courts have upheld the rights of authors to enforce the GPL 'free' software licence, which inspired Creative Commons licensing for artistic works.
Once the restaurant has been notified, an ex-post facto addition of a credit may bring the use of the images into compliance with the licence terms, but it does not void the copyright violation that has already occurred. It is up to the OP to decide whether that would satisfy his grievance. He would be within his rights to demand that the infringing prints be removed from the restaurant and destroyed.
The only question that remains unanswered is, if the OP were to take action against the restaurant, what commercial value would be placed on the images, since he has released them under a CC-BY license, which allows commercial use (with attribution). In English law, should it come to a court case, the OP is entitled to recover damages for the infringement, i.e. that which he has been deprived by the defendant's use of his work. The defendant might argue that the value of the images has been diminished by the CC-BY licence.
However, I should note that in at least
one US case relating to Cisco Systems' violations of the GPL, a settlement was reached which involved Cisco making cash contributions to the Free Software Foundation.
Giving something away for free (under certain conditions) does not necessarily imply that it has no value. There is a parallel with some cosmetics companies suing people reselling their product samples, even though they were given to dealers at no charge, under condition that they were not for resale.
edit: The answer to the question of value would lie in what price the OP would have agreed to license the images to the restaurant with no attribution, should they have approached him to use them outside the terms of the CC licence.
not only is copyright violation not theft , but it isnt even clear that copyright has been violated
a more likely scenario is that someone made a derivative work and creditted him on their websiste etc, then sold the print of it to the resteraunt (it doesnt specifically say on that licence that attribution has to be on every print)
No, it is clear that a licence violation has occurred.
The terms of the licence state
CC BY 2.0 said:
You are free: to copy, distribute, display, and perform the work
...
Under the following conditions:
Attribution You must give the original author credit.
[emphasis added]
The works were being displayed without attribution, therefore the terms of the licence have been breached. Ipso facto, copyright has been violated.
QED.
* s7 of the full, legal text of the CC licence sets this out explicitly - "This License and the rights granted hereunder will terminate automatically upon any breach by You of the terms of this License."
