- Author
- Worthey, J. A.
- Title
- Geometry and Amplitude of Veiling Reflections.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Report
- NBSIR 87-3525, March 1987, 38 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- illuminating; visual perception; reflection; color; surface properties
- Identifiers
- veiling reflection
- Abstract
- The problem of veiling reflections in flat reading matter is examined in three theoretical analyses. These assumptions are made: (1) The surface is shiny, so that surface reflections can be treated as creating a mirror image; (2) The light source has a non-zero area; (3) Insofar as it matters, the reading material has non-zero area also. The first analysis assumes that the reader can tilt the reading material. The extent to which a larger luminaire forces him to tilt farther from his line of sight and from the incident light is then computed. The second analysis assumes that the luminaire image is not avoided. Then, the smaller the luminaire is, the brighter its image will be, relative to a diffuse white surface; this effect is expressed in a formula and in graphs. The overall implication of the first two analyses is that while veiling reflections are not negligible with spherical illumination, the worst light sources are those of intermediate size, whose image is hard to avoid, yet brighter than in the spherical case. The final analysis shows that when veiling reflections cannot be avoided, they desaturate colored objects. For instance, spherical illumination reduces the accessible volume in the CIELAB uniform color space by 37%.