Addressing the Limits of Human Colour Perception with Spectrophotometers

The visual world is made up of numerous colour combinations, and for years mankind has been working to control each one. Image Source: Flickr user Mary-Lynn

I remember once asking a boy in the throes of a tantrum if he was ‘seeing red.’ The look of confusion on his face told me he was unfamiliar with the saying, but the flushed colour of anger that painted his cheeks made it obvious where that term originated. Colour perception is a part of our daily lives that we often take for granted and rarely stop to consider.

We live in a visual world that relies upon colour perception to tell us almost everything: which foods are safe to eat, which wire to connect to which power source, and even how we determine the way a person feels just by the tone of their skin. We hardly ever stop to think of exactly how dependent we are on the differing shades and hues we see each day. The reality is that colour perception has become a highly complex and intricately precise area of scientific study and our need to control colour perceptions has driven us to new standards in colour measurement and techniques. Our eyes are incredibly complex, but because the brain tries to filter out extraneous information, we don’t have the visual acuity needed to accurately measure colours. That’s where colorimetric instrumentation and spectrophotometers come in.

Visual discrimination

Due to the various nature of colour perception, mankind learned early on that visual discrimination was very subjective to the viewer’s unique experience or perspective. The optical memory abilities of the human-eye are very limited and based on our own personal standards. Take, for example, the image below. One person may say that the fruit in the bowl appears purple, while another may say blue.

Some may agree that the blueberries in this bowl are indeed blue, but based on colour perception and variation, hues of purple and red can also be detected by various optical viewpoints. Image Source: Flickr user jeffreyw

The fact is there are probably a dozen different ways people could describe their colour perception regarding that bowl of berries and it’s no wonder we are all so confused.The colour ‘blue’ itself has been reinvented more than a dozen times. For example, Crayola©™crayon company has developed over 19 different names and variations of the original blue since the standard box of crayons was first produced in 1903. Although this has given us more adjectives to use in describing colour in various shades, it has made it extremely difficult to label colours for precise matching or classification.

This creates a huge problem when a customer requests a specific colour of product and expects it to match the shade or hue they had in mind. It is nearly impossible to accurately describe a colour to another person or to have the ability to reproduce that colour based on our own colour perception. As technology has advanced, we’ve needed a way to communicate colours across various industries and fields of study in order to produce accurate results. Knowledge and understanding of colour perception has become a requirement of modern living.

How do we do it? Using light to measure colour

Researchers and scientists have been working continuously to find ways of predicting colour appearance, and yet can only quantify it under specialized conditions. Over the past century, colour measurement standards have been linked to the International Lighting Commission (Commission Internationale de l’Eclariage, referred to as CIE), which established the system of colorimetry and colour matching.

Development began in the 19th century when scientists were able to link the relationship between light and the human colour vision receptors in the eye. As studies progressed, scientists found that colour perception matched all the basic rules of mathematics. With this fundamental knowledge came the development of colour television and many other modern electronic display devices. Based on the three primary colours of red, blue, and green, a wide array of colour perceptions can now be created.

Colour technology links the study of light to visual perception receptors in the human eye, which scientists found relate directly to basic mathematical principles. Image Source: Flickr user 55Laney69

This basic system worked well when quantifying colour in relation to a light source, but when taking this information and applying it to the majority of other manufactured goods that come in the form of solids or liquids, colour measurement needed to entail a higher level of technology. Quantifying object colour needed to take into account several variables which continually interfere with measurement, such as sample size, illumination, surrounding colour, and angle of observation. Colorimetry and spectrophotometry provided the answer, and these new applications moved a step beyond basic colour assessment to comprehensive technological evaluation.

Colorimetric instrumentation and spectrophotometers

Colorimetric instrumentation and spectrophotometers are able to provide standardized conditions that ensure colour perception measurements that are consistent and repeatable. Both types of instrumentation serve a purpose in colour perception for various applications. Colorimeters are highly adaptable for many production and quality control applications through the use of fixed-geometry optical viewing, a single light source, and three photocells that are typically set to international standards. Spectrophotometers, on the other hand, perform at an even higher level, using many more sensors to separate light and provide the ability to measure the spectral reflectance of an object. You will find this application widely used in colour formulation and research applications.

Colour perception is important no matter what application you are dealing with, and the ability to accurately and consistently measure colour is invaluable to many industries. Whatever your needs may be, it is important to choose instrumentation that meets development standards and encompasses various markets and product uses. HunterLab offers reliability and over ten decades of experience in colorimetry and spectrophotometry, and has embraced all the growth and changes in colour technology. We provide solutions for colour measurement that span multiple industries and research areas and take pride in their commitment to the many various applications of spectrophotometers. For answers to all your colour measurement needs, contact HunterLab today.