>Is anyone able to say if these posters (reproduced electronically) >are covered by copyright?

Yes they are, at least without circumstances that might have led to the copyright lapsing.  The copyright is more than likely owned by the studio which considering the consolidations and transfers in the past few decades might be a bit tricky to track down unless they're well-known films.

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Online resources for film/TV studies may be found at ScreenSite
http://www.tcf.ua.edu/ScreenSite