Lacquer crafts are distributed over Southeast Asia from the East Asia such as China and Korea, Vietnam, Myanmar
including Japan. Especially, a Japanese lacquer is well-known traditional crafts. Its color is jet black but people feel
different texture because it is made by complicated and multi step manufacturing process such as coating and polishing
with different materials. In this report, we focus polarization properties of surface structures on black Japanese lacquer.
All states of polarization can be expressed Stokes parameters, which are consisted on four elements as s0 to s3. These parameters are effective for the evaluation of the state of polarization. The polarization information of surface structure of Japanese lacquer can be visualized by using an imaging Stokes polarimeter by dual rotating retarder and analyzer. It is possible to evaluate surface character by comparing the degree of polarization. It is effective to evaluate the surface by using the polarization information.
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.
Comprehension of a sentence under a wide range of delay conditions between auditory and visual stimuli was measured
in the environment with low auditory clarity of the level of -10dB and -15dB pink noise. Results showed that the image
was helpful for comprehension of the noise-obscured voice stimulus when the delay between the auditory and visual
stimuli was 4 frames (=132msec) or less, the image was not helpful for comprehension when the delay between the
auditory and visual stimulus was 8 frames (=264msec) or more, and in some cases of the largest delay (32 frames), the
video image interfered with comprehension.
Humans can put different colors together and categorize them as "red", "yellow", or "orange" etc. This is called
categorical color perception. We applied this property of human color vision to area segmentation for road images in
order to compensate color tone change of road images depending on light condition on a road. Basic map of categorical
colors is constructed in the L*a*b* space based on the color naming experiment. Area segmentation was done by
assigning one of the 14 categorical colors to each pixel. Results were successful, even without any noise reduction
technique, A shifted database of categorical colors for images with orangish tone is also prepared by trial and error.
Pseudo-color-constancy is successfully obtained for the images of orangish tones using the shifted database. To deal with
the lightness change depending on the change of sunlight along the time of day, an appropriate value was added to the
lightness of each pixel of the original image. Satisfiable area segmentation was obtained in this case, too. This method
indicates the possibility of implementation of color constancy property for color image processing of road scene.
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".
This paper will present a literature survey on the basic aspects of the possibilities for color presentation in the
peripheral visual field and the results from some experiments from two laboratories in Japan and in Sweden. The
method used was a color naming technique that included hue and saturation/chromaticness estimations of color
stimuli of different eccentricity. In one laboratory, the size effect was also examined. Unique hue components of
the stimuli were derived from the results of hue and saturation/chromaticness estimates. The results from the two
laboratories showed similar tendency despite the differences in the experiments. The results showed that an
increase of the retinal temporal eccentricity to 40 deg caused impaired color appearance especially for red and
green colors. Smaller color stimuli, subtending 2 deg of visual angle, were perceived as less chromatic as larger
color stimuli, subtending 6.5 deg of visual angle. The results are in line with some earlier studies showing that
blue and yellow colors are better perceived than green and red in periphery.
In this study, we examined the influences of color media and mode of appearance on color appearance by evaluating four attributes of color such as saturation, hue, blackness, and categorical color. CRT display and color charts were used as color stimuli both were presented in the surface-color mode as well as in the aperture-color mode. Results indicated that saturation, blackness, and categorical color names strongly depend on the mode of appearance, while the results of hue does not clearly show such a tendency.
There are many white objects around us. For example, there are white papers, white clothes, white ceramics etc. Therefore the whiteness perception of white objects plays an important role in the impression of lighting as well as perceived color of colored objects. Whiteness perception of white objects is influenced by color temperature or chromaticity of the light sources more than the colored objects. Ayama et al. has been investigating the relationship between color temperature or chromaticity of the light sources and the whiteness perception of white objects. In this paper an objective method for quantifying whiteness perception is studied. We attempt to investigate the relationship between chroma derived from some recent color appearance models and whiteness perception. Mainly the relationship between chroma derived from CIECAM97s and whiteness perception is discussed. As a result of the investigation, it was made clear that as the chroma becomes lower the whiteness perception becomes higher and that the whiteness perception is equal if chroma is equal even if the hue varies.
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.
Categorical color naming experiment was carried out in the entire visual field using five test stimuli, R, Y1, Y2, G, and B which appear red, dark yellow, bright yellow, green, and blue, respectively, at the center of the visual field. The observer reported color appearance of the test stimuli using only one of 13 color terms (11 basic categorical color terms, yellowish-green, and aqua-blue). The test stimuli were presented at 0 deg and from 10 to 80 deg in the eccentricity with 10 deg step for each of the 8 directions. The constant color name region where the same color name as used at 0 deg was obtained was clearly larger for Y2 and B than those for R and G, while that of Y1 was in between. Approximate size of the constant color name region of monocular viewing extended 30 deg in the nasal and upper, 40 deg in the lower, 70 deg in the temporal visual fields. Outside of the region, the categorical color responses became unstable and in the far periphery achromatic color names such as white or gray often appeared in all of the test stimuli.