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What colour is this or which color is this?

What colour is this or which color is this?

Color can be a complicated topic. When someone asks “What color is this?” or “Which color is this?”, it may not always be straightforward to provide an answer. There are many factors that can affect color perception, including lighting conditions, individual differences in vision, and the fact that color exists on a continuum rather than distinct categories. This article will provide an overview of some key considerations when identifying colors, look at how language and culture influence color names, and explore some of the science and psychology behind color vision and perception. With over 2 million distinguishable colors perceptible to the human eye, color is a complex and fascinating topic.

The Factors That Affect Color Perception

There are several important factors that influence how we perceive color in the real world:

Lighting Conditions

The characteristics of the light source illuminating an object determine what wavelengths of light reach our eyes. Different types of light bulbs, the time of day, and exposure to direct or indirect sunlight all influence the colors we see. An object that appears red at nighttime may look completely different under the midday sun.

Background Colors

The colors surrounding an object also affect perception, due to simultaneous contrast effects. Identical shades can appear lighter or darker depending on what colors are next to them. Context is everything when it comes to color.

Individual Differences

People have variations in their color vision based on the cones in their eyes that detect different wavelengths of light. About 1 in 12 men and 1 in 200 women have some form of color vision deficiency. This makes their color perception different from the average person.

Continuous Spectrums

Color is not divided into absolute categories. It exists along a continuous spectrum. There are no clear lines between where one color stops and another starts, making color classification difficult.

The Subjective Nature of Color

Because color depends on perception and interpretation, there is a degree of subjectivity when identifying colors. Here are some key considerations:

No ‘True’ Color

Objects do not have any one ‘true’ color independent of an observer. Their color depends on the visual system looking at them and the context. A red apple is only red because of how human vision works and processes wavelengths of light reflecting off the apple.

Culture and Language

The culture and language people are part of shapes color categorization. Different cultures and languages divide the color spectrum into distinct categories in different ways. Some languages only have words for a few basic colors, while others have many more colorful distinctions.

Descriptors and Comparisons

When trying to specify a certain color, people often use comparisons (“it’s more green than blue”), reference objects (“it’s tomato colored”), or visual descriptors (“it’s very saturated”). These help communicate a color based on shared points of reference within a culture, since the perception is subjective.

Mental Representation

People tend to have an idealized mental representation of familiar colors that likely does not match the huge variation that exists. When comparing a color to a mental representation, mismatches may occur. This can make it tricky to answer “what color is this?”questions accurately.

The Science and Biology of Human Color Vision

The mechanics of how people see and process color at a biological level helps explain why color can be so complex:

Cones and Rods

There are special photoreceptor cells called cones and rods in the retina at the back of the eye. Cones detect color, while rods detect brightness. There are three types of cones that respond preferentially to short (S), medium (M), or long (L) wavelengths of light.

Opponent Process Theory

According to opponent process theory, information from cones is processed by opponent neurons. Some respond to blue vs yellow, others to red vs green. This sets up antagonisms in how color is coded neurally.

Color Opponency Principles

Due to opponent coding, colors are perceived in oppositional pairs. No color can be both red and green, or both yellow and blue, at the same time. This underlies key perceptual elements of color vision.

Color Constancy and Memory

The visual system also exhibits color constancy. Objects maintain relatively stable color appearances despite changes in lighting conditions. Visual memory plays a role in this phenomenon.

Individual Differences in Color Vision

There are some common variations in how people perceive color:

Color Blindness

Color blindness refers to a decreased ability to distinguish certain colors, due to anomalies in cone cells. The most common forms are difficulties distinguishing reds and greens, or yellows and blues. About 1 in 12 men and 1 in 200 women have some degree of color blindness.


At the opposite end of the spectrum, some people have an extra type of cone cell and may experience enhanced color vision. This condition is called tetrachromacy and is more common in women. Tetrachromats may be able to perceive 100 million colors, compared to 1 million for the average person.

Color Agnosia

In very rare cases caused by specific types of brain damage, people may develop color agnosia. This results in an inability to perceive or recognize any colors at all, seeing the world only in black, white, and shades of grey.

Measuring and Classifying Colors

Given all the complexities of color, standards have been developed to systematically measure, quantify, and classify colors for scientific and industrial use:

The Visible Spectrum

Visible light exists along a spectrum from about 400-700 nanometers. The longest wavelengths are perceived as reds and the shortest are seen as violets. This range comprises all the possible colors humans can see.

Wavelength (nm) Color
380-450 Violet
450-495 Blue
495-570 Green
570-590 Yellow
590-620 Orange
620-750 Red

The CIE Color Space

In the 1930s, the International Commission on Illumination (CIE) established a standard color space based on how humans see color. It allows any color to be plotted in terms of its coordinates on x, y, and z axes. This provides precise numerical specification of colors.

Color Models

There are also many color models that represent colors mathematically in terms of sets of numbers, such as RGB values. Each color can be specified by a triplet or quadruplet of numbers corresponding to different reference axes.

Color Matching Systems

Systems like Pantone provide standardized palettes of paint or ink colors for design use. Each color has an assigned number or code for consistent reproduction on different materials.

Practical Issues in Color Identification

Despite scientific measurement and classification methods, identifying colors is not always straightforward:

Lighting Conditions

As mentioned earlier, the lighting conditions where a color is being viewed significantly affect its appearance. A “blue” object under tungsten light may look completely different under LEDs.

Background Effects

The surrounding colors influence how a color looks due to contrast effects. A “light blue” may appear much darker or lighter depending on context.

Individual Perception

Differences in individual color vision, mental representations, and descriptive vocabularies make consensus difficult. Your “green” may be very different from someone else’s “green”.

Specifiers and Comparisons

Using modifiers like “light”, “muted”, or “milky” can help specify a color. Comparisons to familiar objects (“terra cotta”, “avocado”) also provide a reference point but aren’t always exact.

Consensus and Agreement

Agreeing on a color ultimately requires building some consensus between parties observing the color. There needs to be shared understanding and alignment on descriptive terms and mental representations being used.


Identifying colors is based on complex physics, biology, neuroscience, culture, language, and psychology. Many factors influence how we perceive and describe colors in the world around us. While there are scientific measurement systems, putting a name to what color something is can still involve subjectivity and subtle complexities in human vision and communication. When trying to determine “what color is this?” in everyday situations, it helps to have an awareness of the issues involved and to aim for building consensus based on a shared understanding of the color being observed. With an openness to exploring nuances in perception and descriptive color language, it’s possible to zero in on accurate color identifications and descriptions.