French painter and experimental artist, born in Paris, son of Victor Vasarely. He studied graphic art and publicity at the École des Arts Appliqués, Paris, 1949–51, and adopted the name Yvaral as a partial anagram of his father's name in 1950. In 1960 he was a founder member of the Groupe de Recherche d'Art Visuel (GRAV), and like the other members he approached art in a scientific spirit: ‘All my work can be reduced to systems of organization used by contemporary scientific research.’ He was strongly influenced by his father and much of his work can be classified as Op art. Characteristically he used devices such as moiré patterns of approaching and receding forms within a shallow depth dimension. His work also included Kinetic sculpture, screenprints, and multiples. From 1975 he introduced digital imaging into his work and between 1989 and 1995 applied this technique to images of Marilyn Monroe and other celebrities. He also worked in an architectural context: one of the most striking examples is an enormous image of St Vincent de Paul (1987) on the side of a five-storey apartment block in the tenth arrondissement of Paris, made from thin steel plates of varying depth, so as to be visible only from an angle or when the sun is low.