Print surfaces are typically classified as matte, semi-gloss, or glossy (though manufacturers have used other terms including, luster, pearl, smooth, etc.). How a print surface is classified is determined by the way it reflects incident light. The best way to view the surface sheen of a print is to view it under specular or axial light. A glossy surface will exhibit a specular highlight, while a matte surface will diffuse the incident light (see Surface Sheen [2]).
Sometimes, light will reflect off of a print differently in different areas of the image. For example, in electrophotographic prints the fused toner can be highly reflective, so the printed areas will be glossy (center image below). However, the surface of plain paper is rough, so the unprinted areas will appear matte. The opposite is sometimes true for pigment inkjet on glossy photo paper, where the inked areas are dull but the surrounding white areas are shiny (right image below). Some high-end inkjet printers apply special gloss optimizers to reduce or eliminate this effect. This variation in reflectivity across the surface of a print is called differential gloss.
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| Image under normal lighting | Dry toner image under axial lighting | Pigment inkjet under axial lighting |