A Study on the Illumination Chromaticity Estimation and the Chromatic Adaptation to Color Images for the Corresponding Color Reproduction

Research Project

Project/Area Number	23500223
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Perception information processing/Intelligent robotics
Research Institution	Nagoya City University
Principal Investigator	TAJIMA JOHJI 名古屋市立大学, システム自然科学研究科, 教授 (50381900)
Project Period (FY)	2011 – 2013
Project Status	Completed (Fiscal Year 2013)
Budget Amount *help	¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000) Fiscal Year 2013: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2012: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2011: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	画像情報処理 / カラー画像処理 / 光源色推定 / カメラ特性補正 / 色順応 / 照明色推定
Research Abstract	The estimation of the illumination chromaticity from a color image was studied. This study is based on the dichromatic reflection model. At first, it was verified that the reflection model holds well for plastics. On that condition, the chromaticity of a one-color object is distributed on a straight line, and the lines corresponding to the multiple objects with various colors cross each other at a single point, which shows the illumination chromaticity. Based on the theory, the method, in which the calibration of the gamma-characteristic of a digital camera and the estimation of the illumination chromaticity are simultaneously achieved, was developed. The raw mode color images from single-lens reflex cameras and their manually segmented images are used for the experiment. The gamma-characteristics of each camera was approximated by hyperbolic functions. By optimizing the parameters for the functions, the accuracy for the illumination chromaticity estimation could be improved.