Adjective modifier

• unknown: From this input data we want to recover an estimate of the unknown illuminant.

• canonical: This is defined to be the set of all sensor responses obtained by viewing all physically realizable surface reflectances under a canonical illuminant.

Modifies a noun

• direction: However, for directional surfaces, the information content of the image will be altered by a change in the illuminant direction.

• tilt: For isotropic surfaces a change in illuminant tilt is effectively an instance of rotation, with the texture properties being preserved.

• intensity: Use lower illuminant intensity at first to make this alignment a little easier, to start with.