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

研究了从彩色图像中估计光照色度的方法。本研究基于双色反射模型。首先，验证了反射模型对塑料的适用性。在此条件下，单色物体的色度分布在一条直线上，不同颜色的多个物体对应的线在一个点上相互交叉，这就是照明色度。实验中使用了单镜头反射式相机的RAW模式彩色图像及其手动分割图像。每个相机的伽马特性用双曲线函数来近似。通过对函数参数的优化，可以提高光照色度估计的精度。

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.