Colors

Touching, tasting, smelling, hearing, and seeing—these are the ways
we get our information about the world, about where we live and
where we work. But the world of humans is primarily a world of sights,
with 90 percent of what we know of the world coming to us through
our vision.

What we see is color. Objects, landscapes, faces all register in our
brains through the light that enters the eye, sent to us from a luminous
—or light-producing—object (such as a red-hot iron or a glowing
incandescent light) or as light reflects off a nonluminous object (such
as a tree or a table). The eye’s retina absorbs the light and sends
a signal, or sensation, to the brain. This sensation makes us aware of
a characteristic of light, which is color.
The visual equipment we use to see light and its characteristic color is
the same for everybody, and when it’s working, it works very well—
the National Bureau of Standards estimates that the human eye can
distinguish over 10 million different colors. However, color does more
than just give us objective information about our world: It affects
how we feel. To know this, we need only recall how a string of grey,
overcast days lowers our spirits or how working in a drab, dull room
leaves us listless.
With so much of what we know and feel coming from what we see,
you’d think we’d all be experts on color. In a way, we are. No one has
to tell you what you’re seeing or how you’re feeling as you sit in the
glow of a late summer sunset. But how would you describe the pink
of that sky? Dazzling? Fleshy? Glistening? Iridescent?
The qualities we assign to our perceptions of colors—to the way they
make us feel—are called indeterminate attributes. They cannot be
measured; rather, they arise from our intuitive experience of color.
These indeterminate attributes provide the mystery of color and range
from the poetic language we use to express our perceptions of color
to the psychological effects of color on our mood.

There are the functional and the non functional colors. The functional it is all about Attraction, Creating Atmosphere, Inform, Structuring, Teaching. Colors must have a communicative function and should attract through color strength. Create atmosphere with the help of cold or warm colors for example.
Inform, as in a hospital where yellow indicated infection. Structure, as in a newspaper where different sections are color coded. Teach for instance through tint blocks which emphasize and clarify certain parts of the materiel.

Natural Color Theory
The most common system of describing colors is the Natural Color System, which is based on research into how humans perceive color. This system is described in the color space, the color circle and the color triangle.

CMYK Color is short for Cyan-Magenta-Yellow-Black.

CMYK is a color model in which all colors are described as a mixture of these four process colors. CMYK is the standard color model used in offset printing for full-color documents. Because such printing uses inks of these four basic colors, it is often called four-color printing.

RGB Color which stands for Red-Green-Blue.

Display devices generally RGB as color model. RGB and CMYK have different color Gamuts (Gamuts simply means the range of colors which can be produced) RGB has larger gamut than CMYK.

Every visual presentation involves figure-ground relationships. This relationship between a subject (or figure) and its surrounding field (ground) will evidence a level of contrast; the more an object contrasts with its surrounds, the more visible it becomes.

When we create visuals that are intended to be read, offering the viewer enough contrast between the background (paper or screen) and the text is important. Text presentations ideally offer at least an 80% contrast between figure and ground. (Black text on a white background is ideal.) If there is not enough contrast between figure and ground, a viewer will squint to view the text, causing eye fatigue.

Color Combinations

Color combinations may pass unnoticed when pleasing, yet offend dramatically when compositions seem to clash. One outcome we seek in the final form or composition, is a successful use of color.

We determine whether or not we are successful by critically assessing the visual balance and harmony of the final composition—balance and harmony are achieved by the visual contrast that exists between color combinations. Planning a successful color combination begins with the investigation, and understanding, of color relationships.

Using a color wheel and a template, the relationships between colors are easy to identify.

Monochromatic Relationship Colors that are shade or tint variations of the same hue.
Complementary Relationship Those colors across from each other on a color wheel.