Human color impression for color sequence with minimum distance

We examine how a row of fundamental six-color (cyclic) sequence affects human color impression. In order to investigate the different effects of two spatial sequences, we consider a hexagonal diagram that is a projection of RGB color space from white to black. The hexagonal diagram corresponds roughly to the hue circle indicated by both hue and saturation in the HLS system. The projected route area indicates the magnitude of naturalness (as in rainbows) for color sequences. The minimum sequence is similar to the order of colors in rainbows, whereas the non-minimum sequence is completely different. Therefore, we proposed a human color impression model using the projected route area indicated by both hue and saturation. We clarified that subjects of nearly all ages have natural impressions when the route area is large and unnatural impressions when the route area is small, and compared the human color impression to the human color impression model.