In this paper, we have clarified the relationship between ambient illumination and psychological factors in viewing of
display images. Psychological factors were obtained by the factor analysis with the results of the semantic differential
(SD) method. In the psychological experiments, subjects evaluated the impressions of displayed images with changing
ambient illuminating conditions. The illumination conditions were controlled by a fluorescent ceiling light and a color
LED illumination which was located behind the display. We experimented under two kinds of conditions. One was the
experiment with changing brightness of the ambient illumination. The other was the experiment with changing the colors
of the background illumination. In the results of the experiment, two factors "realistic sensation, dynamism" and
"comfortable," were extracted under different brightness of the ambient illumination of the display surroundings. It was
shown that the "comfortable" was improved by the brightness of display surroundings. On the other hand, when the
illumination color of surroundings was changed, three factors "comfortable," "realistic sensation, dynamism" and
"activity" were extracted. It was also shown that the value of "comfortable" and "realistic sensation, dynamism"
increased when the display surroundings were illuminated by the average color of the image contents.