Principles of the present color systems are briefly described and their limitations are discussed. Since one of the most significant limitation is that color appearance cannot be represented by these color systems, factors influencing color appearance are mentioned and variations of color apearance by these factors are described in order to show how and in what degree colors change. Modes of color appearance has been recently considered as an important factor caused by a higher level of the visual system. Therefore, its effects on color appearance is shown using the results obtained in an categorical color-naming experiment.
