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 surroundings, 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.
Yellow
text on a white background or blue
text on a black background, are difficult to read due to the low level of
contrast between figure and ground.
An occurrence known as 'simultaneous contrast'
may happen when opposing colors are placed in close proximity to each other.
Text may appear to vibrate, or cast a shadow. Eye strain and fatigue will result
if a viewer focuses on a document displaying similar properties for an extended
time period.
Some color combinations, such
as red text on a blue background, cause illusions when positioned
together.
When choosing complementary colors, fully
saturated colors will offer the highest level of contrast. Choosing from tints
or shades within the hue family reduces the overall contrast of the
composition.
Sensitivity to Colorblind Deficiencies. The
Design of visual documents or signage without thought to the overall contrast
level between figure and ground can be problematic for people with site
deficiencies. If a visual document uses color to relate
important information, insure that no information is lost, or potentially
misunderstood, when the color is not available.
