Modeling Gonio-spectral Reflection Properties of Paper Sheets for Efficient Gonio Imaging

In this paper, we proposed a gonio-spectral reflection model for paper sheets based on the dichromatic reflection model. The model was the linear combination of the surface and body reflection components. The surface reflection component was assumed as Torrance-Sparrow model, and the body reflection as Lambertian reflection. Several paper sheets in wide range of roughness were measured, and the results were compared with the model. The model showed good correspondence with the measurement results, and it was confirmed to be appropriate for paper sheets. Parameters of the model were properly estimated from 5 data points for papers without sharp peak reflection such as paper for plain copy, Japanese washi paper and matt-coated paper. The proposed model is effective for efficient gonio imaging, since the parameters are estimated from small number of data points.