Caponigro on Colour
The Temperature of Colour - Warm or Cool
An essential quality of colour is temperature. Temperature can be used to attain a colour balance, enhance spatial relationships within an image and elicit psychological responses. Understanding and exploring the dynamics of temperature in colour can benefit any visual artist.
There are physical characteristics of colour linked to temperature. The colour temperature of light (Kelvin degrees) is determined by measuring a black body radiator (an object heated so that it emits light). As the physical temperature of the object rises, colour transitions from red (long wavelengths — low energy) to blue (short wavelengths — high energy) through ROYGBIV (red, orange, yellow, green, blue, indigo, violet). When it comes to light sources, physically, blue is warmer than red.
There are also psychological qualities of colour linked to temperature. Psychologically, blue is cooler than red. These associative qualities of colour with regard to temperature are almost universally accepted. This is due in large part to our physical environment — water is blue, plants are green, sunshine is yellow, fire is red.
Using the qualities of one sense (touch) to describe the qualities of another (sight) can be a tenuous affair and may lead to ambiguity and confusion. The more precise a language is the more useful it is. The language of HSL (hue, saturation, luminosity) is a very precise language. When using the language of HSL, hue values mark a position measured in degrees (0-360) on a colour wheel.
- 0 red
- 30 orange
- 60 yellow
- 90 yellow green
- 120 green
- 150 blue green
- 180 cyan
- 210 green blue
- 240 blue
- 270 purple
- 300 magenta
- 330 blue red
Absolutely warm and cool colours can be found at 0 (red — no warmer colour) and 180 (cyan — no cooler colour) degrees. Determining whether one colour is warmer or cooler than another can be measured by its proximities to these poles. A line between 90 (green yellow) and 270 degrees can be used to broadly demarcate warm colours from cool colours; colours on the right (towards red) are warm while colours on the left (towards cyan) are cool. The association of yellow with the sun, a warm light source, subtly skews the associative quality of warmth towards yellow (60) and away from blue; as a result, colours above the line between 0 and 180 tend to seem warmer than colours below it — ie: while both are equally distant from red (0), orange (30) seems warmer than blue red (330).) While one colour can be seen as warmer or cooler than another colour, each colour also has warm and cool components — there are warm yellows and cool yellows, warm blues and cool blues, etc. (Where numerical classifications of colours define hues very specifically — 1 degree per hue, 30 degree spread per linguistic colour — linguistic specifications of colours — red, orange, yellow, etc. — define broad ranges of hues.) Defining the warm and cool endpoints of any linguistic colour is useful at a coarse level of granularity but becomes increasingly subjective at a fine degree of granularity. At what point does blue become purple? At what point does blue become green?
It’s possible to describe the adjustment of hue simply in terms of warming and cooling.
Photographic colour adjustment strategies rely on adjusting a balance in each of three complements.
- R — C
- G — M
- B — Y
The line between 90 and 270 degrees divides the colour wheel in two halves — warm colours (right) and cool colours (left). Two points on the colour wheel can be considered absolutely warm (0) or cool (180). Moving any colour towards or away from one of these points either warms or cools it.
The colours in the image plotted on the Apple colour picker.
The warm colours.
The cool colours.
An image with a colour dynamic that is warm and cool, which uses both warm and cool variations of the two dominant hues.
Each set of complements has a warm and cool dynamic.
- R (warm) — C (cool)
- G (cool) — M (warm)
- B (cool) — Y (warm)
These three complementary axes have different warm/cool dynamics with respect to the three colour primaries - RGB.
- red (warm red) — cyan (cool blue): warm/cool
- green (cool green) — magenta (cool red): cool/cool
- blue (warm blue) — yellow (warm green): warm/warm
You can make a field of colour appear more dynamic, complex and three-dimensional by preserving or introducing a variety of warm and cool components in it.
The temperature of colour carries spatial associations with it. Warm colours tend to appear to be nearer than cool colours. Again this is universal. It can be overturned by many factors. Some factors are related to colour — saturated colours appear nearer than desaturated colours or a progression from light to dark may be the primary element that establishes spatial hierarchy. Other factors are not related to colour — for instance, placement and overlap in composition may be primary spatially, overriding colour relationships.
Colour balance, spatial proximity, association — these are just three of the uses of warm and cool colour dynamics in images. Whether you are adjusting pre-existing colour relationships or creating new ones, having thoroughly explored the warm and cool dynamics of hue, you can apply that knowledge towards the realisation and enhancement of your images.
