Caponigro on Colour
Simultaneous Contrast
How red is red? That depends in part on its context. We see colours in relationship to other colours in our field of vision. The appearance of any one colour is modified by the presence of other colours. (This is a perceptual effect not a physical effect; while we experience it, we cannot measure it physically.)
Once you identify the elements in play, you can predict the effect. Simultaneous contrast can occur between any one or multiple components of the three elements of colour — luminosity, hue or saturation.
Place dark colours next to light colours and the dark colours will appear darker and the light colours will appear lighter.
Place cool colours next to warm colours and the cool colours will appear cooler while the warm colours will appear warmer. (Additionally, complementary hues increase each other’s saturation.)
Place saturated colours next to less saturated colours and the desaturated colours will appear less saturated while the saturated colours will appear more saturated. (Additionally, the desaturated colour will appear to contain a cast of the saturated hue’s complement.)
Want to make a colour appear lighter? Make it lighter or make surrounding colours darker, or both. Want to make a colour appear warmer? Make it warmer or make surrounding colours cooler, or both. Want to make a colour appear more saturated? Make it more saturated or make surrounding colours less saturated, or both.
Contrast (or lack thereof) is the engine that drives colour dynamics. To intensify a visual effect, increase the contrast in the appropriate components of colour. This effect is intensified between adjacent colours. It is further intensified if one colour surrounds another, partly or entirely. (If a colour dynamic is particularly intense it may create the visual appearance of a line separating the two fields of colour. Op artists often use these effects to create highly dynamic visual effects that appear to pulsate or move.)
Colour management doesn’t yet accommodate these kinds of perceptual effects. Standard colour correction strategies don’t tend to address them. But you can incorporate them into your colour adjustment methods for greater precision and/or expression. All you need to do is take note of them and make appropriate compensations to achieve the result you desire.
Surround a colour with a lighter colour and it will appear darker. Surround a colour with a darker colour and it will appear lighter.
Surround a colour with a less saturated colour and it will appear more saturated. Surround a colour with a more saturated colour and it will appear less saturated.
Surround a colour with another hue and its hue will shift towards the complement of the surrounding colour. Surround a colour with two different hues and it will appear to be two different colours.
You can surround two different colours with two other colours to make them appear the same.
When a truly neutral colour is surrounded by a saturated hue it no longer appears truly neutral. To achieve a neutral appearance the hue of the neutral colour needs to be adjusted away from neutral towards the surrounding colour.
Complementary colours in proximity with one another make each other appear more bright and saturated, when mixed saturation is reduced in the resulting colour.
Exercise
Because it’s difficult to separate other forms of image content from colour, colour exercises are best performed abstractly. While it’s useful to check numerical values for colours and colour relationships, because these exercises are perceptual (often incorporating physiological and psychological responses that are not physically measurable), determine your answers visually. Train and trust your eye.
- Make one colour appear to be of different luminosities by surrounding it with appropriate colours.
- Make one colour appear to be of different saturations by surrounding it with appropriate colours.
- Make one colour appear to be two colours by surrounding it with appropriate colours.
- Make two different colours appear the same by surrounding them with appropriate colours.
