This paper introduces the work ‘the color of light‘ or ‘the painting of light’ by rainbow control which uses rainbow holograms. Usually paintings are made with colored paints and they are seen with light. However we cannot experience the true colors of light. The artist paints rainbow holograms on the film directly as in real painting, creating a variety of colors like dyes. Rainbow holograms have red, green, and blue light which can be mixed to create additional colors. The artist paints, with light, on the film directly, making rainbow holograms. This is done instead of making a hologram of an existing work, so the work is more vivid and immediate. The process makes forms like paintings and adds colors on them. There was an exhibition, titled ‘Reinterpretation of spectrum’, in Seoul Korea from December 26, 2008 to January 17, 2009 showing these works. In addition there was a holography workshop. This paper introduces rainbow holograms, how to mix colors of light using rainbow control, and the set-up for making small and large holographic paintings.