1 Introduction: Local and global perspectives on gloss Humans are readily able to evaluate the glossiness of objects. However, the mechanisms of gloss perception are not understood, and psychophysics in this area is sparse. The presence of bright specular highlights is the most important factor in the perception of gloss (Beck and Prazdny 1981). The effects of highlights are especially dramatic when two images with and without highlights are placed side by side (figure 1). Remote effects of highlights on gloss perception Perception, 2005, volume 34, pages 565 ^ 575 Julia Berzhanskayaô, Gurumurthy Swaminathan, Jacob Beck‰, Ennio Mingolla Department of Cognitive and Neural Systems, Boston University, Boston, MA 02215, USA; e-mail: juliaber@cns.bu.edu Received 22 December 2003, in revised form 15 September 2004 Abstract. The perception of a glossy surface in a static monochromatic image can occur when a bright highlight is embedded in a compatible context of shading and a bounding contour. Some images naturally give rise to the impression that a surface has a uniform reflectance, character- istic of a shiny object, even though the highlight may only cover a small portion of the surface. Nonetheless, an observer’s impression of gloss may be partial and nonuniform at image regions outside of a highlight. A rating scale and small probe points indicating image locations were used to investigate the differential perception of gloss within a single object. Gloss ratings given by observers were not uniform across a surface, but decreased as a function of distance from a highlight. When, by design, the distance from a highlight was uncoupled from the luminance value at corresponding probe points, the decrease in rated gloss correlated more with distance than with luminance change. Experiments also indicated that gloss ratings may change as a function of estimated surface distance, rather than as a function of image distance. Surface continuity affected gloss ratings, suggesting that surface and gloss processing are closely related. DOI:10.1068/p5401 ô Current address: Krasnow Institute for Advanced Study, George Mason University, Fairfax,VA 22030, USA. ‰ Author deceased March 4, 2003. Figure 1. Glossy (left) and matte (right) objects. (Note that the perception of glossiness is likely to be diminished by the process of photographic reproduction, relative to what is visible on a computer monitor.)