Visual Effects of Wooden Floor Patterns with Contrast Variation

As a wooden floor is composed of many wood elements, homogeneity of colors or grains of the floor would be lost occasionally. This study aims to determine image characteristics which objectively describe visual irregularities of a given wooden floor pattern, and to examine the effect of these characteristics on visual impressions of the floor patterns. Three parameters, inter-element contrast, intra-element contrast and magnification, were set up to generate 27 kinds of wooden floor patterns systematically by using a computer graphics technique. These floor images were subjected to multi-resolution contrast analysis to calculate two contrast values as the image characteristics which corresponded to inter-element contrast and intra-element contrast, respectively. Also, the contrast values were corrected using a human contrast sensitivity function in consideration of the dependence of spatial frequency. The floor patterns were also provided for sensory evaluation by 36 subjects. They observed and evaluated each wooden floor pattern projected on a horizontally placed screen of the same scale. The wooden floor pattern involving both larger contrasts tended to evoke visual irregularity more easily. Also, the contribution of both contrast to the visual irregularity was almost the same.