基于视觉心理物理学和fMRI成像方法的颜色恒常性机制研究

color constancy is a phenomenon where the perceptual color of one surface remains unchanged despite changes of the spectral composition and intensity of illuminants. This project aims to investigate the effect of chromaticity of the illuminant on the color constancy mechanisms of color normal and color deficient people by visual psychophysics and functional magnetic resonance (fMRI) imaging technology and models of color constancy mechanisms were also built. Firstly, the project investigates the color constancy mechanism from the photoreceptoral stage to the higher level visual cortex with illuminant changes from the neutral to chromatic illuminants which only caused changes of red-green opponent channel responses; secondly, the projects investigates that with illuminants changes which only caused changes of blue-yellow opponent channel responses; eventually, color constancy models, which were about the color constancy mechanisms from the photoreceptoral stage to the visual cortex with illuminant changes producing responses changes of both of two chromatic channels, were built for color normal and color deficient people and were verified by experiments. This project investigates deeply and systematically color constancy mechanisms of color normal and color deficient people, which can provide theoretical principles for the research on color reproduction of spectral imaging system under different illuminants conditions, remote sensing, object detection, machine vision and so forth.

颜色恒常性指的是当光源光谱构成或强度发生变化时，人类视觉系统对同一个物体表面的颜色知觉保持不变。本项目旨在通过视觉心理物理学方法和功能性磁共振(fMRI)成像方法针对正常色觉者和异常色觉者探索光源色度对颜色恒常性机制的影响，并在此基础上建立模型。项目首先探索从标准光源变化到彩色光源仅引起红-绿通道信号变化时正常色觉者和异常色觉者从视网膜锥体层到大脑视觉皮层的颜色恒常性机制；然后探索仅引起蓝-黄通道信号变化时的颜色恒常性机制；最后，针对正常色觉者和异常色觉者，建立一般色度光源下，即同时引起红-绿通道和蓝-黄通道信号变化时，视网膜层锥体的适应性和大脑视觉皮层的激活性构成的颜色恒常性机制模型，并通过实验验证模型。本项目对正常色觉者和异常色觉者大脑中的颜色恒常性机制进行深入、系统地研究，为光谱成像系统在不同光源下的颜色再现、遥感探测、目标检测、机器视觉等领域提供了理论基础。

颜色恒常性指的是尽管光源的强度和光谱构成发生了变化，但我们仍然能感知到物体表面本身的颜色没有发生变化。为了达到颜色恒常性，人类视觉系统采用多种策略试图从进入视网膜的光线中过滤掉光源。国内在颜色视觉领域的研究主要集中在人眼的辨色特性、彩色对比度和色貌模型理论等方面 。与颜色恒常性相关的研究主要集中在应用研究领域，如颜色恒常性算法的研究。项目的主要研究内容为：二维模拟场景下红、绿、蓝、黄色光源下正常色觉者的颜色恒常性机制研究；二维模拟场景下红绿色觉异常者的颜色恒常性机制的研究；三维真实场景下红、绿、蓝、黄色光源下正常色觉者的颜色恒常性机制研究；三维真实场景下光源照射时间和观察背景对颜色恒常性的影响研究。实验结果表明：红色光源下，观察者的匹配结果遵循光源评估模型，绿色光源下观察者的匹配结果遵循von Kries适应模型；色觉异常者为了达成颜色恒常性在红色和绿色光源下做的调整主要是通过红绿颜色控制完成亮度的调整；RGB-LED光源下的颜色恒常性与光源色度有关；对光源的完全适应比对背景中彩色物体的快速参考在颜色恒常性中起的作用更大。本项目研究成果可为RGB-LED光源的设计、光谱成像系统的颜色再现、目标检测、机器视觉等领域提供理论基础。

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