optek Colour Measurement

Colour measurement is originally based on comparison to existing colour standards, like real examples, tables etc. The human eye was the very individual indicator for a colour e.g., already being green or still being yellowish. A reproducible distinction of colors is impossible, if it is not measured under defined conditions. The visible wavelength range is around 380 to 740 nm, whereas UV and NIR cannot be seen by human eyes.

There are several colour definitions, such as RGB (additive coloring) or CMYK(subtractive coloring). Beside the colour itself there are parameters describing differences: brightness, saturation and gloss.

For instance, for safety and traffic signs the DIN EN ISO 7010 gives a definition of colours to be used. There are many norms with color definitions for almost any product. However, if in the industry two products should be compared to have 100% the same colour, it is obvious that a precision measurement technique is needed to check for reproducible colours. The quality control is one important use case for colour measurement.

If a cleaning step (CIP) is started, a colour sensor can quickly identify, if coloured sample is still present in the production line, or if the pipes and vessels are clean. Product differentiation is another example: