In this study, we investigated how the luminance ratio of the surround field (Ls) to that of the central field (Lc) influence
the perceived blackness of the central field in a simple configuration of concentric circle (Experiment 1) and in digital
images of masterpieces (Experiment 2). Results of Experiment 1 showed that perceived blackness of the central field
becomes more blackish and deeper as the contrast between Lc and Ls increases. Results of Experiment 2 showed that
perceived blackness of black area surrounded by relatively bright area in artistic images is stronger than the perceived
blackness given by the same luminance contrast between the center and surround in a concentric circular configuration.
In this study, two experiments were conducted to clarify the relation between RGB values and perceived blackness. In
the first experiment, the average RGB values of black surface areas in the test stimuli where observers begin to perceive
the areas 'black', and further another average RGB values where observers perceive the areas 'really black' were
determined. Results indicate that to realize a 'really black' surface, RGB values should be lower than those of the
original image in some pictures. In the second experiment, how and to what degree the RGB values of black area affect
the visual impression of artistic picture was investigated. Three dimensions, "high-quality axis", "mysterious axis", and
"feeling of material axis", were extracted by factor analysis. Results indicate that the Art students seem to be more
sensitive in the evaluations along the "high-quality axis" and "mysterious axis" than the Engineering students, while the
opposite tendency is shown in the evaluation along the "feeling of material axis".
In this study, we conducted the experiment to compare the whiteness perception of Finnish and Japanese observers. The rank order of perceived whiteness among seven nearly white Munsell chips (Value is 9.25 or 9.5, Chroma is 0, 0.5 or 1.0) under the fluorescent lamps of correlated color temperatures of 3000K, 5000K, and 6700K was determined. Observing condition employed in the two laboratories was exactly the same as well as the experimental procedure. In 3000K condition, the results of Japanese and Finnish observers agreed with each other quite well, while as the correlated color temperature becomes higher, the results from the two laboratories showed different tendencies. Negative correlation was found between the whiteness rank order and the metric chroma for all of the results.