The purpose of this study is to examine gray matching between dark and ambient condition and to improve visibility
using result of gray matching experiment in mobile display and target luminance is 30000 lux for experiment. First of
all, for measuring visibility on ambient condition, the patch count experiment is conducted by investigating that how
many patches can be seen at original images under the ambient light. The visibility in ambient condition was significant
in comparison to dark condition. Next, the gray matching experiment is conducted by comparing gray patches between
dark and ambient condition using method of adjustment. The participants responded that the white or bright gray patch
could not find same brightness patch under ambient condition. To confirm the visibility improvement through the result
of gray matching experiment, visibility is measured under the ambient light after simple implementation. It was same
procedure of the first visibility experiment. After applying the gray matching curve, visibility was more improvement.
Statistic T test result between patches applied gray curve and maximum of dark condition was not significant. It means
that visibility was not different between original patches of dark condition and patches applied curve of ambient
The purpose of this study is to examine the difference in perceptual brightness enhancement per image category through perceptual brightness measurement. Perceptual brightness is measured via psychophysical experiment and brightness enhancement is performed by TMF (Tone Mapping Function). The classification process is comprised of two steps. It is possible to classify histograms into six groups. The three different TMFs for each category selected using the criteria and TMF application strengths. A psychophysical experiment to measure perceptual brightness enhancement was carried out. The experiment was to determine the equal perceptual brightness point between an original image and the corresponding set of TMF images. The results showed that the mean luminance for each category is significantly different. The results from brightness matching indicate that perceptual brightness enhancement is dependent on image category. We can propose that image category should be considered for advanced brightness enhancement methods.