Any meaningful conversation of Pointillism will, in all likelihood, include a mention of Divisionism and maybe even Chromoluminarism. As painting techniques or theories they are interrelated and sometimes used interchangeably, but art historians do make a distinction.

Pointillism is the term that refers to the specific technique of applying oil colors as tiny dots — some as small as 1/16th inch — that, viewed as a whole, comprise an apparent composition. The term Pointillism was first used by art critics to poke fun at the style but it stuck as the respectable and accepted name of this specific technique.

Pointillism was the name given to the work of French painter Georges Seurat, who took the techniques of Impressionism — visible brush strokes, pure bold color, depiction of changing light and movement — in a new direction, which he referred to as “chromoluminarism.” By studying optical effects and color theory, Seurat reasoned that paint colors could remain pure as they are applied to the canvas, rather than being pre-blended, and through the process of “optical mixing” result in what the eye sees as a shimmering luminosity when viewed from an appropriate distance.

American physicist Ogden Rood took issue with the prevailing theory that the eye itself could mix colors and that the resulting composition was brighter than its components. He detailed the science behind the phenomenon in his 1879 treatise on color theory, “Modern Chromatics,” which became a reliable reference for Neo-Impressionists.

Divisionism is the name given to the theory that defied the popular practice of blending colors on the artist’s palette before they are applied to the canvas. Divisionism is based on “dividing,” or breaking down, mixed colors into their purest components. Van Gogh, Picasso and Henri Matisse were no doubt influenced by Paul Signac’s theories put forth in his book, “D’Eugène Delacroix au Néo-Impressionnisme,” published in 1899 and considered to be the definitive treatise on Neo-Impressionism, which includes Pointillism and Divisionism.

Thus Seurat combined Pointillism and Divisionism in creating his works. His famous “Sunday Afternoon on the Island of La Grande Jatte,” perhaps better known as “Sunday in the Park,” is considered the ultimate testimony to the visual effectiveness of his technique. The large painting, with its estimated 3.5 million points of color, took him two years — 1884 and 1885 — to complete.

This may be one of the reasons why there is a very small legion of Pointillist painters. Among the ranks of Pointillists, in addition to Signac, are Camille Pissaro, the Italian Angelo Morbelli, Henri-Edmond Cross and Georges Lemmen.