I just wanted to add some thoughts on this 
definitely heated but really interesting topic 
that has surfaced from time to time on this 
forum.

I think that owners of cels who make scans and 
pictures of them don't own a copyright in those 
scans and pictures.  One of the threshold 
requirements of copyright is originality.  This 
originality requirement is actually a very low 
standard, as even a slight amount of creativity 
will suffice.  But, it seems well-settled that 
in order to obtain a copyright upon a 
reproduction of a work of art, the work must 
contain some substantial, not merely trivial, 
originality.

Now, the argument that a person has a copyright 
in the scans and pictures they made of their 
cels probably runs along one of two paths, 
either (1) they did a lot of work in making 
those reproductions and should be entitled to 
something or (2) the scans are not exactly like 
the underlying cel--some of the colors might be 
a little darker or lighter in the scan than in 
the original.  Neither of these arguments, 
however, have proved successful.  (1) Time and 
effort alone are not sufficient to find 
originality, and (2) the minor variations in 
color from the cel to the scan or picture would 
likely be found insignificant, unintentional, 
and not expressive of the owner's own artistic 
viewpoint.

One case is illustrative:  In 1983, Susan 
Meyer's book entitled "A Treasury of the Great 
Children's Illustrators" was published.  The 
book contained reproductions of original 
illustrations from, among other titles, "The 
Wonderful World of Oz."  Michael Hearn, an 
author of several books concerning children's 
illustrators, sued Meyer saying that some of her 
reproductions were also reproduced in his 
book, "The Annotated Wizard of Oz," and thus 
infringe on his copyright of those reproductions.

The court determined that Hearn did not have a 
copyright in those reproductions--the 
reproductions fell outside the subject matter of 
copyright because of the lack of originality.  
Differences between Hearn's reproduction and the 
original, such as the cowardly lion being more 
brown in the reproduction than in the original, 
were found to be insignificant, unintentional, 
and not expressive of Hearn's artistic viewpoint 
(if he indeed had one).  Similarly, the court 
rejected Hearn's recount of the long, time-
consuming, and allegedly artistic process Hearn 
went through to create the reproductions--
photographing the key block from the original 
illustration, dropping all other colors; having 
each of the secondary colors hand-drawn on 
acetate requiring the tracing of the original 
plates in India ink or with coated mylar; etc.  
In the end, as mentioned above, time and effort 
alone are not sufficient to establish 
originality.

* Hearn v. Meyer, 664 F. Supp. 832 (S.D.N.Y. 
1987).

A quick note on ISPs: In addition to whatever is 
in the web-hosting contract with the ISP, ISPs 
are definitely required to take down infringing 
material upon notice or else be subject to 
liability.  See 17 U.S.C. sec. 512 (2000).  I 
would hope (emphasis on "hope"--I don't know for 
sure) that the ISP would at least check to see 
if the person notifying them of infringing 
material holds a copyright in that material.  
Otherwise, one might imagine a scenario where 
people would abuse the law (e.g., "You outbid me 
in that eBay auction???  Well, I'm going after 
your cel gallery!!!")  So, if you don't own the 
copyright in what someone is posting (see above 
discussion), I think it might be a bad idea to 
complain to the ISP.  You might be successful or 
unsuccessful (depending on whether the ISP 
checks for the copyright), but you might also 
find yourself in trouble for bringing a 
harassing or frivolous claim.

Final thought: There is a difference between 
what is the law and what is just courteous.  I 
think it's a good idea to ask before you take 
images off of someone's site, regardless of 
whether they have a copyright in that image or 
not.  Remember, though, this does not 
necessarily get you off the hook with whoever 
actually does own the copyright.

- jason

More notes: (1) I'm only talking about U.S. law, 
and (2) this is an academic discussion, not 
legal advice.