Brightness perception of light source colors in dense fog

The characteristics of our color vision are affected by various visual envi ronments. In this experiment, we examined how colored lights look in dense fog. We used 12 kinds of colored light as a test stimulus. At first, in the absence of fog, subjects matched brightness of all the test stimuli with a reference white light adjusted to 0.1 cd/m(2) or 0.5 cd/m(2) in luminance, respectively. They then evaluated the apparent brightness of the test stim uli in dense fog with magnitude estimation of 10 grades. In the presence of fog, test stimuli containing a yellow component were given the highest poi nt value of brightness, while test stimuli containing a blue component were given the lowest point value of brightness in fog. We are confident that i n a visual environment involving fog, these results will be extremely helpf ul and practical.