This example is what is typically called a “paintover”. It is a common (yet still unethical) method of trying to change the source enough to call it original. The artist will take a photograph or piece of artwork and bring it into their art software (i.e. Photoshop) and digitally paint on top of the source material. It is not the same as “copying” or “referencing” where the artist would have the source material off to the side of their new work and copy the source by sight alone.
In the case above, the entire pose and anatomy have been taken from Renato Casaro’s classic Conan poster for use in this album cover. It makes the new artwork easily comparable and is infringing on the copyrights held by the original work.