Preferred Racial Skin Color Reproduction in an Image based on Race Classification

Preferred skin color reproduction is an important factor for improving the image quality of display devices and systems. Therefore, this article presents a race-selective preferred skin color reproduction method for the case of multiple races in a single image. First, the proposed method detects skin regions using a focus map and skin candidate map. Next, the race of each detected skin region is classified by comparing the Euclidean distance of the average chromaticity for each detected skin region with a database of racial skin colors. Based on this classification, the racial preferred skin color for each detected skin region is then selected from candidate racial preferred skin colors that are predefined in a database generated through an observer’s preference test. Finally, the skin color is reproduced toward the preferred skin color. Experimental results confirm that the proposed method can achieve race-selective preferred skin color reproduction in the case of multiple races in a single image. c © 2015 Society for Imaging Science and Technology. [DOI: 10.2352/J.ImagingSci.Technol.2015.59.2.020504] INTRODUCTION Preference colors are typically determined according to the observer’s preference, and are an important subjective measure for image quality evaluation of display equipment. The preference indicates the degree of satisfaction of the observer and is generally enhanced by reproducing the colors of sky, grass, and skin.1 Among these colors, skin color is one of the main factors in preferred color reproduction, as humans tend to perceive people before anything else in an image based on recognizing the skin color.2,3 Therefore, the skin color needs to be enhanced to become more natural for the viewer. Various skin color reproduction methods have already been studied. Kao proposed color reproduction using a color transformation matrix.4 Sanger modeled the preferred skin color area using an ellipse and proposed three preferred skin color ellipses according to the ethnic groups of Asian, Caucasian, and African.2 Yendrikhovskij proposed the enhancement of perceived naturalness using a comparison between reproduced color and preference colors.5 Kim proposed mapping toward the preferred skin color region using an affine transform.6 Nachlieli proposed sensitive skin color enhancement to correspond to human preferences regarding the appearance of people based on CIELab color