In the US (united-states) copyright protection is only afforded to work with at least a minimal degree of originality, as was held in Feist Publications, Inc., v. Rural Telephone Service Co., 499 U.S. 340 (1991), (see also the actual text of the decision) The Court's decision included the statement that "The sine qua non of copyright is originality."
Bridgeman Art Library v. Corel Corp., 36 F. Supp. 2d 191 (S.D.N.Y. 1999) established that "slavish copying" does not produce an original work, and the results are not protected by copyright in the US. (A number of other countries have since followed the same logic.) "Slavish copying" is any process, however technically complex or laborious, that produces or attempts to produce an exact reproduction of the original, or as near to an exact reproduction as the medium and technology allows. Such copies are often in a different medium than the original source.
Therefore, an exact or designedly exact conversion of a work to another medium does not produce an original work, and no separate copyright attaches. If the original work is not under copyright, neither is the converted copy.
Additions to the copy, such a a menu, or added captions, may be protected by copyright. But a further copy taken from the enhanced copy but not including any of the enhancements or additions will not infringe such a copyright, and will not be an infringement of any copyright if the original source was out of copyright.
Reconstruction of a damaged work that attempts to restore it as exactly as possible similarly does not create a new copyright, because this is not considered an original work either.
In short, if a film is out of copyright (aka "in the public domain") a Blu-Ray version has no new copyright on the images or sound track. Additions may be protected, but a copy of the disk that omits all such additions will not infringe.