Allows you to select a bitmap file or procedural map to use as a specular map.
The specular map maps an image to the specular component of the image. The specular map is mapped in exactly the same way as the diffuse map, only the picture in the bitmap only appears in areas of specular highlight.
When the amount spinner is at 100, all the specular color is provided by the bitmap.
In metal materials, the Diffuse color tints the specular map. Specifically, the color from the specular map is multiplied by the Diffuse color (including a diffuse map, if one exists).
In non-metal materials, the Specular color multiplies only reflection maps.
Specular mapping is used primarily for special effects (such as placing an image in a reflection) because it doesn’t occur naturally. The important thing to remember is that, unlike Shininess or Shininess Strength mapping that alter the intensity of the specular highlights, specular mapping alters the color of the specular highlights.