ABSTRACT
Contrast is the rate of change of grey tones from black to white – it is described as ‘high’ and ‘low’. Images with normal contrast will have a regular distribution of tones, from full black through all the shades of grey to pure white. Contrast can be adjusted in image-editing software using either the contrast slider or a tone curve. Film contrast is altered by intentionally under- or overexposing and over- or underdeveloping it to compensate. Film manufacturers use a standard chart to show how their film reacts to light, to different development times and to different developers. The tone curve tool can be used to lighten or darken an image but can also be used to increase contrast by lightening the highlights and darkening the shadows.
