Determination of gloss quality

Abstract

A method and apparatus for obtaining a basis on which the gloss quality of a sample surface of a sample, such as a paper sheet, can be determined by illuminating the sample surface and registering the intensity of the reflected light. With the intention of enabling several different types of gloss variation investigations to be made on a sample surface essentially in accordance with known principles of gloss facet approximation, it is proposed, among other things, that the sample surface is exposed in an image registering area by controlled rotary movement of the sample surface through the image registering area or by controlled rotary movement of the image registering area over the sample surface, wherein the intensity of the light reflected from a plurality of spatially well defined part-surfaces of the sample surface is registered several time during this rotary movement while, at the same time, determining the positions of the part-surfaces in the image registering area, and in turn the viewing angle, so as to establish what we here define as an image volume which is representative of the registered light intensity as a function of the position of the part-surfaces within the sample surface and of the respective viewing angle.

Dependencies are inferred from the claim text.