Also spelled ekphrasis, ecphrasis is a technique of writing about a work of visual art in great detail, like when a writer includes a vivid description of a painting in her novel.
Ecphrasis is a literary device, a description of art which is so expressive that your reader can imagine it in detail. John Keats' famous "Ode on a Grecian Urn" is one well-known ecprhasis, a detailed reflection on a specific work of art. Ecphrasis can also be spoken or take other artistic forms — for example, your painting of a sculpture is also an ecphrasis, as is the song you wrote describing Vincent Van Gogh's Starry Night.