Published papers

Basic information

Name AZETSU Tadahiro
Belonging department 国際文化学部 文化創造学科
Occupation name 教授

Title

Lightness and chroma enhancement for food images considering Helmholtz– Kohlrausch effect

Type

Joint work

Journal

Optical Review

Volume

24

Number

3

Pages

301-309

Publication date

201706

Author

C. Ueda, T. Azetsu, N. Suetake, E. Uchino

Review

[Refereed]

Language

English

Summary

The color appearance of a food image is very important for making it look delicious. Many food images acquired in low illumination environments do not give delicious impressions because of the deterioration of their color appearance. We propose an image enhancement method to improve the color appearance of a food image acquired in a low illumination environment. In the proposed method, the lightness of each pixel is first enhanced within a color gamut on an equal hue plane in the CIELAB color space. The boundary of the color gamut is given by a lookup table calculated in advance. Then, when the hue of the pixel is attributed to foods, the chroma is enhanced within the color gamut. In this case, we consider Helmholtz–Kohlrausch (H-K) effect, which indicates the relation of the hue, chroma, and lightness in human visual perception. According to H-K effect, the perceived lightness increases as the chroma is enhanced. Therefore, the perceived lightness is preserved after the chroma enhancement, so that the food image is not too enhanced. To verify the effectiveness of the proposed method, experiments are conducted using several food images.