How we change what others think, feel, believe and do
Hue contrast is a measure of how easily we distinguish between two adjacent colors (hues).
Two areas with a high hue contrast will be easy to separate. An object which has a high hue contrast in comparison with its background will be easy to see. Areas with low hue contrast will blend together and be more difficult to visually separate.
Blue and yellow contrast strongly, but blue and green have a lower hue contrast. Two shades of any hue with similar frequencies will have low contrast.
Opponent Process Colors contrast above/below here are easy to separate:
Lower contrast similar hues above/below here are more difficult to separate:
Color wheels are often arranged such that colors on opposite sides of the wheel are contrasting complements, as in this trigeminal (RGB) wheel, where the RGB colors are opposite their inverse CMY hues:
The contrast between two items, whether visual, auditory or whatever allows us to more or less easily say 'this is one and this is the other'. It also lets us mark the boundary between the two, saying 'this is where one hue ends and another begins'.
Complementary color pairs are, color-wise and mathematically, of maximum difference to one another, and so create the maximum contrast. When complementary color pairs are mixed, the result is gray. This is because the mathematically difference is due to one being made up of what the other is not. Combining them additively hence leads to a monochrome result.
Opponent process colors are naturally contrasting because of the way that the eye and vision system is structured into red-green, blue-yellow and black-white neuron 'wires'.
A person wearing red clothes in a group of others with blue clothes will stand out If everyone is wearing red, nobody stands out.
Images which have a lot of bright hues (high amplitude) can be so over-stimulating that even if there are hues that contrast, the riot of color that is presented exhausts the eye so much that there is less energy available to pay attention to any one thing. In other words, if there are many things that equally attract attention, no one thing will hold attention for long.
Hue contrast is different and complementary to tone contrast, which
Camouflage works partly by using hues that are similar to the background (mottling also helps break up the outline). Animals which are prey to others often have such coloring in order to remain hidden. Keeping very still also helps this when predators are good at detecting motion.
Pay attention to the contrast between foreground and background in an image, especially in the focal point which is intended to attract the eye first. Use hue contrast to make things stand out or fade into the background, depending on what you seek to portray and make people feel.