Now, more than ever, it is very important to achieve a consistent surface quality during the production and processing of surface-treated materials (such as papers, plastics, metal or wood surfaces). A uniform and defined surface quality must be ensured in almost all industrial segments. Variations in glossiness can result from manufacturing defects, supplier changes and material fluctuations. Often, these lead to complaints in quality control or even rejection of the material. Especially in recent years due to increasing demands of customers, it is particularly important to be able to make a flawless, objective assessment of the gloss.