Perception of different color contrast stimuli was studied in the
presence of light scattering: in a fog chamber in Clermont-Ferrand and in
laboratory conditions where light scattering of similar levels was
obtained, using different light scattering eye occluders. Blue (shortest
wavelength) light is scattered in fog to the greatest extent, causing
deterioration of vision quality especially for the monochromatic blue
stimuli. However, for the color stimuli presented on a white background,
visual acuity in fog for blue Landolt-C optotypes was higher than for red
and green optotypes on the white background. The luminance of color
Landolt-C optotypes presented on a LCD screen was chosen corresponding to
the blue, green, and red color contributions in achromatic white stimuli
(computer digital R, G, or B values for chromatic stimuli equal to RGB
values in the achromatic white background) that results in the greatest
luminance contrast for the white–blue stimuli, thus advancing the
visual acuity for the white-blue stimuli. Besides such blue stimuli on the
white background are displayed with a uniform, spatially unmodulated
distribution of the screen blue phosphor emission over the entire area of
the screen including the stimulus C optotype area. It follows that
scattering, which has the greatest effect on the blue component of screen
luminance, has the least effect on the perception of white–blue
stimuli.