Understanding Light & Photography
Additive colours are RGB – Red Green and Blue. When you add these together, you get white.
Subtractive are CMY – Cyan, Magenta and Yellow. Add these together and you’ll get black.
Complementary colours appear opposite each other on a colour wheel.
Objects appear coloured mainly because their surface pigments absorb some wavelengths but reflect others. For example, leaves are seen as green because they reflect green wavelengths and absorbing the rest. In white light, a leaf appears green. The denser the pigments and the stronger the light the more intense or saturated the colour appears. If the leaf is shiny, it reflects some white light, reducing the intensity of the colour. If the leaf is in shade or dim light, the colour is muted. In red light no green light is reflected and the leaf appears black.
Oil on water diffracts light and produces interference. As a result you see colours from the same angles: a prism refracts it (bends light of different wavelengths differentially) to produce spectral colours. Various combinations of absorption, reflection, refraction and scattering effect light as it passes through the atmosphere, often producing colour casts. Skylight, for example, is often blue giving a blue cast in shadows.
Colour vision becomes weaker in dim light. In low light conditions we tend to see in black and white. However, colour film records any colour present, however faint. Pictures taken in dim light often show surprising colour strengths. We notice strong colours more readily than muted hues — particularly if these are distant from us. However, in photographs, the more subtle shades of colour are recorded clearly.
Although terminology may differ, most systems define colour in terms of three qualities:
• Saturation (intensity or chroma); and
• Brightness (luminance or value).
Hue is the property of colour that gives it its name, distinguishing it from other colours; e.g. yellow, red, green, blue, purple, etc.
Saturation is the relative purity, vividness, or intensity of a colour. The stronger or more intense a colour is, the more ‘saturated’ it is. A brilliant red is said to be a high saturation, a soft yellow is said to be of low saturation. Saturation is
dependent on hue. The black, white, and greys of black-and-white photographs do not convey colour saturation.
Brightness is the third dimension of colour. It means the lightness or darkness of a colour. Brightness is similar to value. Many photographers confuse brightness with saturation. Brightness and saturation are not identical but are two separate dimensions. However, in colour photography, a change in one is often accompanied by a change in the other.
Saturation and brightness produce different tones of a hue.
Using a Colour Wheel
The order of the colours in the wheel is the one in which they naturally fall when white light is passed through a prism to form a spectrum-red, orange, yellow,
green, blue, and purple. The wheel is often divided into six or more equal areas, each representing one of the primary, secondary or tertiary colours. On the colour wheel, each hue is represented by its mid-value, the colour that has the
maximum intensity. There is many possible variations of each colour or hue: for example, yellow ranges from orange yellow to green yellow. But in a colour wheel, only the mid-value of each hue appears. The colour circle is an abstract
diagram: its purpose is to help you locate the middle values in relation to each other. There are no ‘lines’ between hues.
The colour circle is a very useful device because it demonstrates fundamental colour relationships so well. Note that each secondary fits between two primaries. This order of colours is exactly the same as in a rainbow.
The closer together colours are on the wheel, the more related and harmonious they seem, because each colour contains some of the colour lying next to it. The farther apart they are, the more they contrast with each other. Colours that are directly opposite each other, such as red and bluegreen are call secondary colour and form the greatest contrast. Hues and the different effects they create when arranged in certain combination provide you with one of your basic tools for composing in colour.
How Light affects Colour
The light used in photography can vary in a number of ways. The three most important are:
• Quality; and
The light of the sun at noon on a clear day is much more intense than sunlight on an overcast day. The light of a small living-room lamp is on the other hand very weak compared with sunlight. The intensity of light affects the colours in your picture. It especially affects their brightness and saturation. Generally
speaking, the more intense the light, the brighter and more saturated that colours appear. Colours appear duller and less saturated on a cloudy or rainy day, than they do in bright sunshine.
Choosing light of a particular intensity, whether indoors or out, is therefore one of the ways you can control the colour in your pictures and make it either strong and poster like or soft and pastel.
The quality of light refers to whether it is high contrast and harsh or from low contrast and soft. Harsh, contrast light, such as the brilliant light from a spotlight or the sun causes distinct highlights and clearly defined shadows. Light, which is soft and low in contrast, such as the diffused light from a floodlight or the sun on a hazy day, causes even illumination with blurred indistinct shadows or almost no shadows at all. The quality of the light affects the brightness and saturation of the colours in a photograph. The harsher and more contrast the light, the brighter and more saturated the colours usually will appear.
The light that comes to us from the sun we call ‘white’ light. However, so-called white light may actually vary considerably in colour. It may contain a higher-than-normal proportion of light in the yellow bandwidth, as the illumination from the late afternoon sun or electric-light bulbs does. On the other hand, it may contain a higher-than-normal proportion of light in the blue waveband like the light in the shade of a building on a day when there is blue sky or light on overcast days. Light may also contain an unusual amount of other colours, green for example, when the light is filtered through the leaves of a tree, red when it is reflected off the side of a red barn, or yellow when it is reflected off a yellow wall.
The Emotional Effect of Colour
Pure strong colours hold the eye and create bold, vital effects. You can use strong to command and direct attention or to create a festive mood. However, you must handle strong colours with care. They dominate all other colours in a picture. They can overwhelm shape and detail, and render a composition unbalanced. So you need to make sure that areas of strong colour support the main interest in your pictures. Many strong colours together result in a struggle for power. A gaudy clash of colours suits some subjects but generally strong colour pictures are more effective if you limit the range of hues and include areas of neutral contrast.
Pure, strong, fully saturated colours can be direct and powerful in their emotional impact. This is the kind of colour children and primitive artists often use. The impact of colour contrast is greater when the colour is fully saturated. An intense, pure red seems to vibrate when it’s next to an intense, pure green. Heavily saturated colours of contrasting hues seem to clash, creating a sense of excitement, drama, and motion.
Strong colour is colour for colour’s sake – the main point of the colour is
its intensity. Strong colours need strong simple design. Bold graphic images can be more effective than a riot of colour, particularly in close up. Primary colours are the most powerful, particularly red. A small area of red distracts attention
from the rest of a scene.
Muted colour is evocative and expressive. You can use muted colours to
convey many different moods; for example, industrial bleakness, rural tranquility, romantic portraits, and dramatic stormy landscapes.
Colour is muted by the addition of black, grey or white — whether through the effects of lighting and exposure or through the presence of de-saturated tones in the subject. Low lighting reduces saturation. Shadows add black and grey, while
reflection, flare and scattering of light de-saturate colour by introducing white.
Shooting into the light also mutes colour, often increasing tonal contrast. You can use exposure selectively to emphasise such light effects — overexposure adds white; underexposure deepens colour and adds black. And finally, with a long lens, you can select an area of distant muted colour to produce a pale unreal effect.
A high key effect is created when a scene is dominated by reflected white light. High key pictures contain large areas of light, desaturated colours with few mid-tones and shadows. Subjects for high key pictures may be found in nature or may be deliberately contrived. A high key tonal range is usually
caused by atmospheric conditions by scattered reflected light in fog and mist and by powerfully reflective surfaces such as snow, sand and water. High key pictures tend to suggest lightness, heat delicacy and happiness. Potential subjects include sand dunes, seascapes, snowscapes and portraits.
A low-key effect is created when light is weak and the scene is dominated by shadows. Low-key pictures tend to have predominantly – dark, degraded colours, generous areas of shadow and few highlights, though they may also contain colours, which appear fairly bold and rich, due to the dark, shadowed background. Low-key effects produced by selecting naturally darkened subject colours – such as violet, black or grey. A blue colour cast due to weak light, fog or mist can lower the tonal range. A low-key tonal range is frequently used for nudes, portraits and stormy landscapes; the mood it evokes is mysterious, dramatic, dark or sensuous.
Colours with opposite characteristics interact strongly when placed together, creating a dynamic effect. Each colour offsets and exaggerates the qualities of the other, so that the colour images stand out boldly from your picture. This colour contrast is strengthened if you support it with the contrast of mass against detail.
Warm and Cool Colours
When you hear photographers talking about ‘warm’ and ‘cool’ colours what they are talking about is hue. In general, yellows, oranges, and reds are considered warm colour, while blues and greens are considered cool. There’s a very
simple reason for calling hues warm or cool. These terms describe the physical sensation we might feel if surrounded by large masses of such colour. We associate red, yellow, and orange with the sun, flame, and fire, which suggest heat. By contrast, cold, deep water is blue or blue-green. Ice often has a green or blue cast. The colours halfway between these warm and cool extremes, such as green-yellow and purple, and more neutral in their effect; they seem neither very warm nor very cool. However, a green hue, which is very close to yellow strikes us as warm, compared with a green that contains more blue. Thus we speak of a warm green or a cool green. In general, any hue is warm if it contains yellow and cool if it contains blue.