Optical color is also known as local color. It differs from arbitrary color in that is based on the perception that is created when dots or brush strokes of different colors are placed near each other in a piece of art. The eye recognizes the illusion of another color as two or more colors seem to mix. The idea of optical colors is used in Pointillism and in newspaper print pictures. Georges Seurat is perhaps the most famous painter who employed Pointillism. He used small dots in his paintings allowing the viewer’s eye to meld them into a coherent piece such as Sunday Afternoon on the Island of la Grande Jatte.
On the other hand, arbitrary colors are those used by an artist to express mood or emotion in a piece of work. The colors used are not realistic but are meant to represent or evoke a feeling. In the use of arbitrary colors, the artist might depict a dog using the color purple or a person’s face in a bright vibrant yellow. Andy Warhol often used arbitrary colors in his work.