A Craik-O'Brien Effect Based Lightness Modification Method Considering Color Distance for Dichromats

Dichromacy, also called as visual impairment, is an inherited disease of defective or abnormal color vision characterized by an inability to recognize certain colors. In this paper, a new lightness modification method based on Craik-O'Brien (C-O) effect was proposed in order to improve the color recognition ability of dichromats. The main idea is to modify the lightness values of the contour parts of the regions which are easy to be confused for dichromats by establishing the objective function of considering color distance, and find the optimal lightness modification value by using the steepest descent method. The modified images will generate C-O effect, which will make the observers produce a visual lightness difference, thus improving the color recognition of the images. The proposed method can retain the information details and overall naturalness of the original color images, making it easier to obtain information and perceive color variations and overall characteristics in the original color images for dichromats. The effectiveness and feasibility of the proposed method is shown in the experimental part by means of the comparison and analysis among the test image, the dichromacy simulation images and the result images obtained by this method.