Painter of the large painting in the poster?

The painting is by Eugène Delacroix, "La lutte de Jacob avec l'ange" (known as "Jacob and the angel" or "Jacob wrestling with the angel"); it was painted in the 1850s on commission for the church Saint-Sulpice in Paris, and that's where Sally and Pablo meet towards the end of the film when they pose under the painting.
You can find it reproduced in books about Delacroix's paintings!