Copyright infringement takes place where there is copying of all or a substantial part of an image
– unless a ‘fair dealing’ or ‘substantial part’ exception applies, or unless it is only the ideas or concepts that have been copied (as opposed to their manifestation in material form). Copyright protection does not apply to an idea, only the physical manifestation of the idea.
At the heart of the matter is the requirement that, in order to create copyright, the author needs to demonstrate that new work has been created through his or her use of 'independent skill and labour'; that is to say, that their new work is not substantially derived from another person's older work. If the new work fails the originality test (which in a court of law would be decided by laymen looking at images side by side and deciding whether or not there was a significant similarity), then such work will not achieve copyright protection.
If the creator of the older work died more than seventy years ago, then copyright in that work will have expired, and anyone will be permitted by copyright law to make a photographic, or any other “slavish copy”.
The US Supreme Court has definitively ruled that a photograph of a painting fails the originality test, and therefore does not create a new copyright in that photograph; but the UK courts have not yet been called upon to decide this issue.
In addition there may be moral rights to consider, as the author of the work has the right to be both identified as such and to object to derogatory treatment of his or her work, where it has been either modified or distorted. These moral rights last for as long as copyright (i.e. for the whole life of the creator), and on death will pass for the next seventy years to the artist’s estate and then his or her successors.
Assuming that an image is copyright protected, UK copyright law nevertheless permits elements of such an image to be appropriated and used in new artworks, on the basis that the new artwork is not substantially derived from someone else's earlier copyright work. In other words, there is no infringement of copyright if the new artwork does not appropriate all or most of someone else's earlier copyright work, but uses inconsequential elements of it together with other images created by the new author; a collage of other people's copyright images might be an example. Having said all that, the particular circumstances of each case will have to be looked at by the courts to decide the matter.
Erring on the side of caution and approaching the owner of the two-dimensional image to obtain a licence for the use of the image would be the better approach as it would avoid triggering a later dispute over potential copyright infringement. The downside of approaching the owner of the work could be a tacit admission that the image is copyright protected when this is debatable. This might require some skilful negotiation and a specialist art lawyer should be approached for this.