White Point Parameters
Specular Highlights
Specular highlights are highlights in an image which are direct reflections of a light source or extremely bright highlights. Specular highlights are usually found on metal, glass, water, or any highly reflective surface. Some white objects will also act like specular highlights.
Avoid using specular highlights as white points. There is theoretically no tone (no ink) in a printed spectral highlight. The specular highlights are the brightest sections of an image and should be "paper-base white." Using a specular highlight to set the white point causes one or two issues. The image's tonal range will generally remain unchanged and therefore uncorrected and the color range will not be neutralized either.
Proper White Point Selection
Specular Highlight Used for White Point Selection