White Point Parameters
Specular Highlights
Specular highlights are bright spots in an image that result from a light source, direct reflections of a light source, or extreme brightness. They are usually found on metal, glass, water, or any highly reflective surface. Some white objects can also produce specular highlights.
Avoid using specular highlights as white points. There is theoretically no tone (no ink) in a printed specular highlight. Specular highlights are the brightest parts 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