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

2013 Fiscal Year Final Research Report

• 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
• Keywords: 画像情報処理 / カラー画像処理

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.