Impacts of lower- and higher- luminance components on the material perception

摘要

Impacts of lower- and higher- luminance components on the material perception Textures of objects underneath the glossy finish resides in the lower part of the luminance histogram of object images, while specular reflections reside in the higher part. We psychophysically investigated which of these luminance components contributes more to material perception. The stimuli were photographs of various material samples from stone, wood, leather, and fabric categories. In addition, we created two types of luminance-modulated images: low- and high-luminance preserved images (LLP and HLP images). The LLP images were created by compressing the luminance contrast in the higher half of the original photographs by 1/5, and vice versa. The LLP and HLP images were presented randomly on the right and left of the original image at the center, and observers were asked to choose which modified image gave material impression closer to the original image. In the results, there were large differences between sample categories in selection ratios of HLP images, suggesting that the contribution of lower- and higher-luminance components to material perception differed among sample categories. We further investigated relations between the choice and spatial frequency subband components of image statistics. We found that the LLP and HLP were chosen in fabric/leather samples and wood/stone samples, respectively, when the images contain richer high spatial frequency components. This is probably because higher/lower luminance components of images included characteristic patterns of each material. These results suggest that the lower-luminance components possibly play an important role in the material perception for the samples with fine selfshading patterns like fabric and leather.