Simple lightness modification for color vision impaired based on Craik–OʹBrien effect

In comparison with the people having the normal color vision, the people with color vision impairment such as dichromats have the difficulty to distinguish the colors in certain combinations. This may pose an impediment of the visual communication in the recent wide spreading of the use of colors. In order to address this problem, in this paper, we propose a novel lightness modification method to improve the visibility of the color image for the color vision impaired. In the proposed method, the lightness modification is only carried out around contours of objects to realize the Craik–OʹBrien effect, which is an perceptual illusion of the contrast, for dichromats. Furthermore, in the proposed method, it is tried to preserve the impression given by original color image by lessening the change of the color as possible while providing the perceptible and comprehensible color image for dichromats. Through some examples, the effectiveness and the validity of the proposed method are verified.