This work is performed as part of the perceptual validation stage in the stereoscopic visualization of computer- generated (CG) images of materials (typically car paints) containing sparkling metallic flakes. The perceived material aspect is closely linked to the flake density, depth, and sparkling; in turn, our perception of an image of said materials is strongly dependent on the image exposure, that is, the amount of light entering the sensor during the imaging process. Indeed, a high exposure may over saturate the image, reducing discrimination amongst high-luminance flakes, affecting the perceived depth; on the other hand, a low exposure may reduce image contrast, merging low-luminance flakes with the background, and reducing perceived flake density and sparkling. In order to choose the right exposure for each CG image, we have performed a user study where we presented observers with a series of stereoscopic photographs of plates, taken at different exposures with a radiometrically color-calibrated camera ,⁵ and asked them to assess each photograph's similarity to a physical reference. We expect these results to help us find a correlation between optical settings and visual perception regarding the aforementioned parameters, which we could then use in the rendering process to obtain the desired material aspect.

Date Published: 8 February 2015
PDF: 8 pages
Proc. SPIE 9396, Image Quality and System Performance XII, 93960N (8 February 2015); doi: 10.1117/12.2077681

Published in SPIE Proceedings Vol. 9396:
Image Quality and System Performance XII
Mohamed-Chaker Larabi; Sophie Triantaphillidou, Editor(s)