Color combinations that lead the eye to focus on a specific element of an image.
The usual contrasting colors on the color wheel are:
- yellow and purple
- blue and orange
- green and red
- black and white
Light and dark can also be a way to add contrast to an image. For example, if you walk around on the night of Halloween, the sun is down so it's dark outside, but a few pumpkins will be lit. Your eye will automatically focus on that light coming from the carved pumpkins so we could say that the orange light from the jack-o-lanterns contrasts the dark.
See Unicef's
Bad Water poster ad for two good examples of contrast: orange and blue, light and dark.