Consider if you have a polished metal ball
, with a bright light source
shining on it. Then you will see a bright reflection
of that light on the surface of the metal ball
. This is one example of a specular highlight
The size of the specular highlight depends on the material of the surface. If we take the previous metal ball example, it will have a very sharp highlight. This would be called a highly specular surface. But take, say, a polished shoe, or a waxed apple. This will still have a specular highlight, but it will be larger and not so concentrated, since the reflection won't be as sharp. This is a less specular surface.
Specular highlights are a special issue in computer graphics, since adding specular highlights to scenes can enhance photorealism.
Various illumination models in computer graphics model the variation of this specular highlight, the most well-known being the Phong illumination model.