Color & Jetness measurement: Fixed or variable aperture

Color Difference Equations for Solid Colors

It is now almost 100 years since, in 1931, the CIE Yxy chromaticity color space was defined by the "International Commission on Illumination (CIE)". To overcome its limitations of not being uniform, the CIE recommended two alternate color spaces since then: CIELAB (or CIE 1976 L*a*b*) and CIELUV (or CIE L*u*v*). They are based on the opponent color theory of color vision, which says that two colors cannot be both green and red at the same time, nor blue and yellow at the same time. During the last years developments of new color difference equations and color spaces were carried out. Their goal was to improve the correlation between visual perception and instrumentally measured values. Additionally, they wanted to permit the use of a single number tolerance for all colors.

The basic building blocks of color measurement

Visual color perception is influenced by our individual color preferences, which are dependent on personal factors (mood, age, gender etc.), environment (lighting, surrounding etc.) as well as our ability to communicate color and color differences. A color looks different in the department store (cool white fluorescent lighting) than at home (warm, incandescent lighting). In order to guarantee consistent color and appearance under all possible circumstances, it is essential to standardize light source, observer and understand the spectral remission data of the object. This information will be the basis for calculation of colorimetric data as it is used for color communication and color QC in production.

Color Measurement of Fluorescent Colors – a CHALLENGE

The world around us is bright and colorful. Neon colors in particular have been back in trend for several years. The prerequisite for this is the use of fluorescent pigments in the paint, plastic and many other industries. Although these have been widely used for many years, the quality control of fluorescent material still remains a major challenge. The following article describes theoretical background of fluorescence, why a standard spectrophotometer is not suitable for the quality control of fluorescent material and what possibilities the new combination of spectrophotometer and fluorimeter offers - especially with regard to predicting the lightfastness of a material.

Color measurement of BLACK

Already in the Stone Age, black based on charcoal was used as one of the first colors ever. The measurement and qualification of black has been a challenge since then, as it reflects hardly any light. On the one hand, special indices are needed because evaluation using L*a*b* values is only suitable to a very limited extent. On the other hand, the selection of appropriate measuring instruments with outstanding technical performance also plays an essential role. The following technical article describes how to raise quality control of deep and deepest black colors to a new level of precision and reliability.