Measuring gloss by digital photography

The measurement of gloss is conventionally made by specialised instruments that determine the ratio of reflected to incident illumination at a single fixed angle. This study investigated whether digital photography with flash illumination could be used as an alternative. Multiple exposures were combined by a high dynamic range (HDR) imaging technique to produce a two-dimensional intensity profile of the reflectance around the specular point. The method was tested for six paper samples of varying gloss, and the results were found to correlate well with instrumental measurements. The image gloss profiles, however, provided more information about the distribution of the reflection over a range of angles and also gave an indication of the surface texture.