Contrast

Contrast is the degree of difference between the lightest and darkest tones of the subject or photographic image. A high-contrast photograph is one where dark tones and bright tones dominate over the mid-tones within the image. The highest contrast image possible is one containing only two tones, black and white, and where no mid-tones remain. A low-contrast image is one where mid-tones dominate the image and there are few if any tones approaching white or black. Without contrast photographic images would appear dull and flat. It is contrast within the image that gives dimension, shape and form. Awareness and the ability to understand and control contrast is an essential skill to work successfully in the varied and complex lighting situations that arise on location and in the studio.

High contrast - Kata Bayer Low contrast - Tracey Hayes

Affecting contrast

Contrast is affected by the difference in the intensity of light falling on a subject and the intensity this light reflects back to the viewer or light-sensitive surface. Light usually strikes three-dimensional subjects unevenly. Surfaces facing the light receive full illumination, whilst surfaces turned away from the light receive little or none. Different surfaces reflect different amounts of light. A white shirt reflects more light than black jeans. The greater the difference in the amount of light reflected, the greater the subject contrast. When harsh directional light illuminates a subject overall contrast increases. The highlight tones facing the light source continue to reflect a high percentage of the light whilst the dark tones in the shadows may reflect little. The difference between the darkest and the lightest tone increases, leading to increased contrast.

The human eye can register detail in a wide range of tones simultaneously. Film and digital image sensors are unable to do this. They can record only a small range of what human vision is capable of seeing. The photographer has the option of recording a selected range of tones or seeking ways of lowering the contrast. In an attempt to visualize how the contrast of a subject will be translated by the photographic medium many photographers use the technique of squinting or narrowing the eyes to view the scene. Squinting removes detail from shadows and makes the highlights stand out. In this way it is possible to estimate the contrast of the resulting image.

Contrast on location

Cloud cover diffuses the light leading to lower contrast images. Shadows appear less harsh and with softer edges. The lighting may be described as being flat and the film or digital image sensor will usually be able to record the range of tones present if accurately exposed. When direct sunlight strikes the subject the contrast usually exceeds the film or image sensor’s capability to record the range of tones. The photographer may have to seek a compromise exposure.

Kata Bayer

Creating contrast

Working in a studio situation where the subject and lighting are under the control of the photographer, contrast is usually by design rather than by any error of judgement. As all the elements that cause contrast are controlled by the photographer it can be created and used to great effect. Placing highlights in shadow areas and deep shadows through mid-tones can create interesting images.