Although concepts are specific to philosophy for Deleuze, Ideas are not, and painters or cinematic directors have Ideas in their own medium, not the medium of the concept.
'Ideas' doesn't mean some kind of paraphraseable argument. The painter, for example, has Ideas - concerning tone, colour, depth etc -which are immanent to what happens on the canvas. They can't simply or indifferently be transposed into concepts.
In this sense Deleuze doesn't share the philosophical hierarchy according to which the concept is a kind of superior language into which others, whether the language of paint, sculpture, or the figurative languages of literature can be translated, as if other languages are only silhouettes of the concept, as if the concept divulges the full truth of these other languages, languages which cannot yet know their own significance.
In each case style is needed – the writer’s syntax, the musician’s modes and rhythms, the painters lines and colours