Generally humans are very  good at distinguishing different levels of brightness but less good at differentiating hues and intensities.

Mixing in (tones, shades, and tints) expands the basic 12-spoke color wheel into an infinite number of colors.

Color Context – It’s important to understand how color behaves when paired with other colors and shapes to use them in the best way possible.

Color is ALWAYS relative, rule laid out by J. Albers. The same identical color can be made to look like two different colors and two different colors can be made to look the same, simply by placing them in different contexts. The reason is that Two colors, side by side, interact with one another and change our perception accordingly. The effect of this interaction is called simultaneous CONTRAST.
The real colors are not altered, only our perception of them changes.

SIMULTANEOUS CONTRAST – most intense when when two colors are complementary.

Darker surrounding color –the central square appears lighter
Lighter surrounding color –the central square appears darker

Two different colors are made to look the same value, saturation, hue, or size

COLOR EFFECTS – Spatial interpretation of the color area in relation to the total visual field. it is how we perceive a color when appears next to another.

Helmholtz-Kohlrausch Effect – Color shift in a simultaneous hue contrast.
Boundaries and outlines can create strange distortions in the way we perceive a color.

Bezold Effect – White and black outlines create completely different visual impressions when the main colors are exactly the same
COLOR

YELLOW as background color-  Vivid and fresh atmosphere. Pattern colors become more soft and light.

BLUE as background color- Mood becomes gloomy. Pattern colors look darker and deeper & sharper.

Breneman Effect – As the background becomes darker, the induced lightening in the image causes all the values to appear lighter. this has the greatest impact on the darkest values. Against a light valued background the lightness contrast causes the image values to appear darker

Complementary colors look the brightest and most vibrant next to each other. The same color can look very different depending on what it’s next to.

AFTERIMAGE EFFECT – Demonstrates the interaction of color caused by interdependence of color.

After staring for half a minute at the left square, shift the focus suddenly to the right square Instead of the usual color-based afterimage that would complement the yellow circles with blue, their opposite, a shape-based afterimage is manifest as diamond shapes –the ‘leftover’ of the circles.

OPTICAL ILLUSIONS

When you have a really big contrast between colors the eye’s jumping from one color to another trying to get the whole picture. That creates the illusion of movement.