Colour perception through the lens of XRite: A seminar by Namashivayam
The session provided an in-depth understanding of how the human eye and brain interpret colour, why those interpretations are often unreliable, and how technological tools like spectrophotometers enable precision, consistency, and repeatability.
07 Jul 2025 | By Sai Deepthi P
Colour perception is a complex interaction between light, objects, and the human eye, with the brain playing a significant role in interpreting what we see. While common folks rely solely on their eyes, printers use measurement tools like spectrophotometers for accurate colour evaluation. “We think we see colour with our eyes, but in reality, it’s our brain doing most of the work, and sometimes, it gets fooled,” said Namashivayam, a pre-sales solution consultant, X-Rite, while delivering a presentation that explored the science behind colour perception and the reasons why objective colour measurement is vital in industrial settings.
He opened the session by posing a compelling question: if the human eye is ultimately responsible for deciding if a colour is acceptable, why is there a need for instruments to measure colour? The answer, he explained, lies in the inherent subjectivity of visual perception. Human judgement is influenced by a host of variables which lead to inconsistent and often inaccurate colour assessments. In critical industries such as printing, packaging, textiles, and plastics, where colour consistency is paramount, reliance solely on visual evaluation is inadequate.
Through visual demonstrations, Namashivayam showed how the same shade appears different depending on the background against which it is viewed. One reason why light booths are equipped with neutral grey panels and controlled illumination is to ensure there is accurate colour perception. This visual distortion is because of the way the brain interprets contrasting elements within the field of view. Similarly, lighting conditions play a significant role. A colour viewed under natural daylight may appear entirely different under store lighting or fluorescent tubes. This is where standardised lighting environments such as D50 for printing and D65 for textiles help minimise these inconsistencies.
Key factors influencing colour perception
Surrounding colours: The same colour can appear different depending on the background. Our brain adjusts perceptions based on surrounding hues.
Lighting conditions: The type of light (e.g., daylight, fluorescent, tungsten) significantly affects how colours are perceived. Industries use standardised lighting like D50 or D65 for consistent colour evaluation.
Visual Illusions: Optical illusions demonstrate how easily the brain can be tricked by light, shadow, and contrast.
Retina fatigue: After viewing a bright colour for a while, the eye experiences fatigue, which affects how we perceive the next colour. A 45-second break is recommended between assessments.
Colour memory: The brain cannot store exact colour values, which leads to inconsistent recall. This is why visual memory is unreliable for precise colour matching.
Mood and emotions: A person’s emotional state can influence colour judgement. A good or bad mood can lead to accepting or rejecting a colour sample.
Colour deficiency: Some individuals, especially men, have red-green colour blindness, affecting how they perceive colours. Tools like the Ishihara test help detect this.
Brain-added colour: The brain sometimes "fills in" colour based on previous visual stimuli, even when no colour is present.
This set the stage for a detailed explanation of how a spectrophotometer works. Namashivayam explained that the device emits light onto a colour sample and measures the percentage of light reflected at each wavelength from 400 to 700-nanometres. He added, “Spectrophotometers don’t have moods, memories, or colour deficiencies. That’s why we need them. Even though we trust our eyes, we must measure with instruments because consistency in colour is a science, not a feeling.”
These reflection values form the fingerprint of the colour, which is unique and allows for accurate comparison, formulation, and reproduction. This fingerprint data is used in calculating LAB values, density, dot gain, grey balance, and other key metrics. The data is also essential for various workflows such as press profiling, ink formulation, and quality assurance in colour-critical production. He described LAB values as coordinates that help locate a specific colour in a three-dimensional colour space. ‘L’ stands for lightness, measuring how light or dark a colour is. ‘A’ represents the green to red axis, while ‘B’ represents the blue to yellow axis. These values, akin to GPS coordinates, help define the exact position of a colour in colour space.
The presentation concluded with an emphasis on the practical implications of objective measurement. A spectrophotometer’s data is not only used for checking quality on the production floor but also for creating brand colour standards, formulating inks, and calibrating printing equipment. Namashivayam stressed that moving from subjective to objective assessment is the only way to ensure colour consistency, especially when products are manufactured across geographies, shifts, and machines.