French postimpressionist painter, born in Paris, one of the originators of the technique known as pointillism. In 1884 Signac began collaborating with French painter Georges Seurat, under whose influence he abandoned the short brushstrokes of impressionism to experiment with scientifically juxtaposed dots of pure color, the defining feature of pointillism. In Signac's pointillist scenes—mainly river or seashore views—the impression of glittering natural sunlight is achieved through placement of the colored dots to create a prismatic effect. After 1900 Signac moved away from pointillism, opting instead for small squares of color to create a mosaiclike effect, as in View of the Port of Marseilles (1905, Metropolitan Museum of Art, New York City). During this period he also produced vibrant watercolors in a more spontaneous, freely composed style.