Basil Gogos Frankenstein Painting

Original photo used to create one of the classic paintings of Frankenstein. One I used as reference to create Creatura 8. The lack of color photography or high expense of it may have influenced the artist to exaggerate the colors even more.  So the question I have in mind is whether it is okay to use a photograph directly if you have full right to?  In this case it is an assignment and the artist is an illustrator.  Basil Gogo's used the image and painted in the way he is best known for.  His palette is unmistakably his own and the mood he has created is almost unapparent in the bland photo reference to the left.