Specular Map

Gives you per-pixel control over both specular strength and color. If the map is greyscale, it only affects strength, not color. Use and RGBA map to control color (and in this case, the alpha channel would control strength).

An object that has a red and green specular map applied that includes an alpha mask.

Figure 1 - with specular_map

A red and green noise texture used for the specular map.

Figure 2 - specular_map

A black and white noise texture used for the alpha of the specular map.

Figure 3 - specular_map alpha

An object with a specular map assigned.

Figure 4 - without specular_map