We found a novel subjective color illusion using a rotating disc.
The disc consists of some black arcs belonging to colored sectors. When this disc rotates, illusory colors are seen in the rings that are traced-out by the arcs. Each illusory color is the complementary color of the sector to which the corresponding arc belongs.
This illusion can be observed even if the disc rotates so fast that we cannot perceive the color of each sector. This illusion indicates that our brain can process the colors of the sectors and output their complementary colors, even though we are unconscious of them.