In the US, Bridgeman v. Corel ruled that faithful copies of public domain works don’t gain copyright protection for being copies of an original. To be copyrighted requires some sort of creative spark, and that spark was entirely contained in the original work; none was introduced in the copying process.

Whether this applies to a Blu‐Ray rip, I will not attempt to discern.

The classical music pieces are old.

The recordings of the classical music pieces are under the copyright.

There was a good article about there at [probably] TorrentFreaks.

Typically the copyright of the recordings derives from the copyright of the performance, and only indirectly from that of the original classical piece. Most recordings are copyrighted, but that’s because recording technology only became hugely prevalent during existing copyright terms.

Looking at it another way, an uncreative recording of a classical performance will be copyrighted for a period of time, but after it expires, a recording of the recording won’t add any further copyright. It’s a bit like how a photograph of a public domain painting is uncopyrightable, but a new painting based on the painting might be copyrightable.

Color correction and transfer to another medium don't create a new copyrighted work as far as I know.