Research Projects

Glossy Appearance Editing for HeterogeneousMaterial Objects

With the proliferation of smartphones and social networking services, the opportunities for individuals to take photographs have increased exponentially. In a previous study, the perceived gloss of an object was reduced by representing as a digital image compared with a real object. It is also known that image editing, such as lossy image compression, can reduce the glossiness of an image. Therefore, the glossiness of real objects may be easily changed in digital images; thus, a method for appropriately editing the gloss in digital images is required for post-processing. In this study, we proposed a gloss appearance editing method for various material objects in a single digital image. The proposed method consists of three steps: color space conversion, gloss detection, and gloss editing. The relationship between the proposed method and the respective reflection models of inhomogeneous objects, metallic objects, and translucent objects was analyzed. Consequently, we determined that the gloss editing of the proposed method is equivalent to editing the specular reflection component of an inhomogeneous object, the grazing reflection component of a metallic object, and the specular reflection component of a translucent object. We applied the proposed method to test images including objects of various materials and confirmed its effectiveness through a subjective evaluation by visual inspection and an objective evaluation using image statistics.

The Reproduction and Evaluation of Star Fields with the Milky Way in a Planetarium

In this study, we investigated the physical factors required to accurately reproduce the Milky Way in star fields in a planetarium using three evaluation indices: faithfulness, preference, and depth feeling. Psychometric experiments were conducted by manipulating three different physical factors (transmittance, representation size and star density) of the stars projected on a dome screen as experimental stimuli. The three evaluation indices were rated by observers for 12 different reproductions of the Milky Way. By analyzing the experimental results, we developed a common model to estimate the scores for each evaluation index by changing the coefficients of the three physical factors. Our proposed model has good accuracy, and each evaluation index can be represented by transmittance, representation size and star density. The weighting values indicate that density reproduction was the pivotal factor for the majority of observers. In contrast, the observers were not affected by the size of the stars in the projected Milky Way.

Modeling perceptions using common impressions: Perceptual "authenticity," "luxury," and "quaintness" for leather

Genuine leather has numerous applications, such as car interiors and clothing, owing to its excellent quality. However, due to the high cost of genuine leather, animal rights issues, and environmental effects of leather processing, artificial leather has increasingly replaced genuine leather. The materials and processing methods used for artificial and genuine leathers are different, resulting in a variety of impressions and shitsukan, that is, the sense of quality of the object. In this study, we focused on the perceptual "authenticity," "luxury," and "quaintness," which are important components needed to achieve the shitsukan of leather used in various products and examined the quantification of qualitative shitsukan using a perception model. We hypothesized that shitsukan can be recognized from the common potential impressions perceived from the properties of a material. Therefore, we developed a method for evaluating shitsukan using representative words for impressions that we perceive in objects and measured their image properties. The physical and psychophysical properties were obtained using several measurements. Multi-angle measuring devices were developed for the measurement experiments. Moreover, several subjective evaluation experiments were conducted to estimate the representative impressions that were potentially perceived in leather. Subsequently, we estimated two independent impressions, "surface shape" and "impression of stateliness" from the properties of leather. In addition, "authenticity," "luxury," and "quaintness," were quantified using simple equations basis the impressions.

Effects of Lighting with Opponent Colors on Promoting Positive Emotional States

It is known that the colors in our surroundings affect emotions. In our previous study, we set up an environment in which a specific emotional state was triggered by conversation and investigated the lighting conditions that promote the emotional state through psychophysical experiments. We found no significant effect on positive emotional states, such as happiness, under a single uniform lighting condition generated by a recall color. In contrast, negative emotional states, such as sadness, were significantly promoted under a single uniform lighting condition. In this study, we investigate the lighting conditions that promote positive emotions through psychophysical experiments. The results of the experiment showed that happiness, as a positive emotional state, could be steadily promoted by illumination with a spatial combination of a color recalled from the emotion and its opponent color.

An Experimental Study of the Effect of Subpixel Arrangements on Subjective Spatial Resolution

This study conducted two psychophysical experiments to evaluate the subjective spatial resolution of displays with different subpixel arrangements. We found that the subjective spatial resolution is affected by the subpixel arrangements even at an angular resolution of 30 cycles per degree. We discuss measurement methods for resolution of the display.

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