[...]Colour may appear different when viewed under a different light source. Brightness is an arbitrarily defined, but carefully standardised, blue reflectance that is used throughout the pulp and paper industry for the control of mill processes and in certain types of research and development programs. Brightness is not whiteness. However, the brightness values of the pulps and pigments going into the paper provide an excellent measure of the maximum whiteness that can be achieved with proper tinting [...].