The colors in this painting are not harmonized. A sophisticated way is to use a color gamut. A simple way is the following: if the mannequin is to be yellow, then the surroundings should be violet. But if the surroundings are blue, the mannequin should be orange. And green harmonizes with red, which isn’t in the painting! I wanted to see how a painting looks with colors that are somewhat dissonant. Looking at this sketch, I keep wanting the mannequin to be orange, with perhaps some reddish parts in shadow that harmonize with the green. Of course, the composition isn’t ideal, either, but this is just a practice sketch.
Update: a friend shared this paper with me on automated color harmonization. The algorithm presented harmonizes colors using various gamut masks–a gamut mask imposed over a color wheel is the most sophisticated way to harmonize colors in a scene. I first read about color gamuts in James Gurney’s Color and Light, an excellent modern book on color theory. The authors of the paper note that naturally-occurring color combinations are often well-harmonized by default. This has always seemed true to me. Betty Edwards discusses this observation, too, in Color, a great book on color theory (but not as advanced as Gurney’s text). Some examples of color harmonization in nature: a blue jay is black, white, gray, and blue. A bluebird is blue and orange. A scarlet macaw is red and green, violet and yellow, black and white. Each of these color schemes is well-harmonized.
Update 11/30/16: Actually, based on the YURMBY color wheel, which is a mathematically accurate color wheel, blue is opposite yellow, which means that blue (not violet) and yellow are complements! Ironically, I realized this by just looking up the YURMBY wheel in Color and Light for another painting I’m working on. I hadn’t used the YURMBY wheel since I read about it years ago. It’s time to start using it.