Colour

Key Questions in Colour Design

  • Does ‘colour’ exist?
  • Why is colour so difficult to define?
  • Why is mixing and combining colours so unpredictable?

Physiologically colour is a sensation of light that is transmitted to the brain through the eye. Tiny differences in wavelengths are processed by the brain into a myriad nuances of colour that convey meaning.

  • Colour, even more than drawing, is a means of liberation (Matisse)
  • Colour must be thought, imagined, dreamed (Gustave Moreau 1893)
  • Colour is like a closing eyelid, a tiny fainting spell (Roland Barthes)
  • Colour precedes words and antedates civilisation (Leonard Shalin)
  • Colour cannot stand alone (Wassily Kandinsky)
  • Colour deceives continuously (Josef Albers)
  • Colour is an illusion, but not an unfounded illusion (C L Hardin)
  • Colour is accidental and has nothing in common with the innermost essence of the thing (Naum Gabo and Anton Pevsner)

In visual perception a color is almost never seen as it really is – as it physically is. This fact makes color the most relative medium in art.

Albers  Interaction of Color 1963 p1

Our perception of colour depends on both physical factors relating to the way the eye registers light and more psychological and cultural factors that affect the way the brain reacts to and interprets colours and their relationships to each other. Because each of us is unique – our eye/brain reactions and cultural experiences differ – we can only talk in terms of generalisations.

Artists and designers have used and experimented with complexities and ambiguities in interactions between physical and psychological dimensions of colour to portray emotions and question the nature of perception.

Colour can only exist when three components are present:

  • a viewer
  • an object
  • light.

It can be said to work on 3 interlinked levels:

Physics of light

The physical process as light bounces off objects and is transmitted to the eye.

Eye/brain physiology

Emotional level as the brain reacts instinctively to interprete the significance of the light signals it receives, evoking sensations that are ‘hard-wired’ by evolution, but also often subjective depending on individual physiology and involving non-visual effects

Symbolic meanings

The cultural level, where the brain associates certain colours and combinations with culturally specific experiences and meanings that have been learned.

In Graphic Design a fourth element is inevitably involved: how to ensure colour consistency when translating designs into and between analog, digital and/or on-line presentations.

References

(to be done)

Cambridge in Colour: Colour Management

Resources:

Cambridge in Colour:  Colour Perception

Color can only exist when three components are present: a viewer, an object, and light. Although pure white light is perceived as colorless, it actually contains all colors in the visible spectrum. When white light hits an object, it selectively blocks some colors and reflects others; only the reflected colors contribute to the viewer’s perception of color.

Prism: White Light and the Visible Spectrum
Human Vision

The human eye senses this spectrum using a combination of rod and cone cells for vision. Rod cells are better for low-light vision, but can only sense the intensity of light, whereas whilecone cells can also discern color, they function best in bright light.

Three types of cone cells exist in your eye, with each being more sensitive to either short (S), medium (M), or long (L) wavelength light. The set of signals possible at all three cone cells describes the range of colors we can see with our eyes. The diagram below illustrates the relative sensitivity of each type of cell for the entire visible spectrum. These curves are often also referred to as the “tristimulus functions.”

Select View: Cone Cells Luminosity



Raw data courtesy of the Colour and Vision Research Laboratories (CVRL), UCL.

Note how each type of cell does not just sense one color, but instead has varying degrees of sensitivity across a broad range of wavelengths. Move your mouse over “luminosity” to see which colors contribute the most towards our perception of brightness. Also note how human color perception is most sensitive to light in the yellow-green region of the spectrum; this is utilized by the bayer array in modern digital cameras.

ADDITIVE & SUBTRACTIVE COLOR MIXING

Virtually all our visible colors can be produced by utilizing some combination of the three primary colors, either by additive or subtractive processes. Additive processes create color by adding light to a dark background, whereas subtractive processes use pigments or dyes to selectively block white light. A proper understanding of each of these processes creates the basis for understanding color reproduction.

Additive Primary ColorsAdditive
Subtractive Primary ColorsSubtractive

The color in the three outer circles are termed primary colors, and are different in each of the above diagrams. Devices which use these primary colors can produce the maximum range of color. Monitors release light to produce additive colors, whereas printers use pigments or dyes to absorb light and create subtractive colors. This is why nearly all monitors use a combination of red, green and blue (RGB) pixels, whereas most color printers use at least cyan, magenta and yellow (CMY) inks. Many printers also include black ink in addition to cyan, magenta and yellow (CMYK) because CMY alone cannot produce deep enough shadows.

Additive Color Mixing
(RGB Color)
Subtractive Color Mixing
(CMYK Color)
Red + Green Yellow Cyan + Magenta Blue
Green + Blue Cyan Magenta + Yellow Red
Blue + Red Magenta Yellow + Cyan Green
Red + Green + Blue White Cyan + Magenta + Yellow Black

Subtractive processes are more susceptible to changes in ambient light, because this light is what becomes selectively blocked to produce all their colors. This is why printed color processes require a specific type of ambient lighting in order to accurately depict colors.

COLOR PROPERTIES: HUE & SATURATION

Color has two unique components that set it apart from achromatic light: hue and saturation. Visually describing a color based on each of these terms can be highly subjective, however each can be more objectively illustrated by inspecting the light’s color spectrum.

Naturally occurring colors are not just light at one wavelength, but actually contain a whole range of wavelengths. A color’s “hue” describes which wavelength appears to be most dominant. The object whose spectrum is shown below would likely be perceived as bluish, even though it contains wavelengths throughout the spectrum.

Color Hue
Visible Spectrum

Although this spectrum’s maximum happens to occur in the same region as the object’s hue, it is not a requirement. If this object instead had separate and pronounced peaks in just the the red and green regions, then its hue would instead be yellow (see the additive color mixing table).

A color’s saturation is a measure of its purity. A highly saturated color will contain a very narrow set of wavelengths and appear much more pronounced than a similar, but less saturated color. The following example illustrates the spectrum for both a highly saturated and less saturated shade of blue.

Select Saturation Level: Low High

Spectral Curves for Low and High Saturation Color