HIERARCHY OF COLOR USAGE GUIDELINES
On This Page: Finding the Information Reading the Information Understanding the Information Other Important Considerations
This page presents a structured
hierarchy of color usage guidelines. It starts at the top level with general statements
of required cognitive performance and proceeds toward more specific graphics requirements
and recommendations that help achieve the top level goals. Where possible links point
to related material elsewhere on the Color Usage Website.
To succeed in using an information
interface the user must
a) find the needed information
b) read it, and
c) understand it.
Finding the Information
1. The graphics shall allow the
user to find desired information with little cognitive effort under all operational
conditions.
1.1 Graphic representations of
more urgent (critical, important) information shall be more salient than those of
less urgent (critical, important)
information, under
all operational
conditions.
More about
salience manipulation.
1.1.1 Temporal modulation (flashing,
blinking, motion) shall only be used to call attention to urgent conditions requiring
immediate attention
or action.
More about temporal modulation.
1.1.1.1 Temporal modulation shall
distract from other important information as little as possible.
1.1.1.1.1 Less distracting forms
of temporal modulation shall be used if adequate.
More
about temporal modulation.
1.1.1.2 Only small screen areas
shall be temporally modulated.
1.2 Color* codes intended to distinguish
different classes of operationally critical data shall
be discriminable under all operational
conditions.
More about
color discrimination.
More
about reflected light.
*Denotes a guideline sufficiently general that the word “graphic” may be substituted
for the word “color”.
1.2.1 Data objects to be coded
by colors shall be large enough to allow color discrimination under all operational
conditions.
More about color discrimination.
1.2.2 Color codes of symbols (or
text) shall be discriminable on all possible backgrounds under
all operational conditions. More about color
contrast.
1.2.3 When the user population
includes users with deficient color discrimination, all color coding
shall be used redundantly
with
other
graphic codes.
or
1.2.4 When the user population
includes users with deficient color discrimination, color codes shall be discriminable
by the largest classes of color deficient users.
More about individual differences
in color vision.
1.2.4.1 When the user population
includes users with deficient color discrimination, caution and warning color coding
(red, yellow, green) shall be used redundantly with
other graphic codes.
Reading the Information
2. Graphic representations of all
operationally critical information shall be legible under all operational conditions.
More about legibility.
2.1 All possible combinations of
colors of symbols (or text) and their backgrounds shall have sufficient luminance
contrast to be legible under all
operational conditions.
More
about luminance contrast.
More about reflected light.
2.1.1 Use of blue or yellow symbols
or backgrounds shall have sufficient luminance contrast to be legible under all operational
conditions.
More
about
blue.
More about outlining and infills.
2.2 If textured backgrounds are
used, symbols (or text) shall be legible on all possible backgrounds, under all operational
conditions.
More
about
pattern
masking.
2.3 All symbols (or text) shall
be large enough and have broad enough strokes to be legible under all operational
conditions.
Understanding the Information
3. When the desired information
has been found and read, the colors* shall allow the user to understand
the information
with little
cognitive
effort
and minimum risk
of error
under all operational
conditions.
3.1 Color* codes intended to identify
different classes of operationally critical data shall
be identifiable
under
all operational
conditions.
More about color discrimination
and recognition.
More about reflected light.
3.1.1 The
number of distinct color* codes intended to identify different
classes of operationally critical data
shall
be small
enough to allow
adequate identification
performance under all operational conditions.
More about color discrimination and recognition.
3.1.2 Color codes of symbols (or
text) shall be identifiable on all possible backgrounds under all operational conditions.
3.1.2.1 Use of saturated background
colors shall not cause misidentification of color codes of symbols (or text).
More
about color contrast.
More about outlining and infills.
3.2 Color* codes shall be used
consistently throughout the work environment.
3.2.1 Each color* code shall be
used to code only a single data category throughout the work environment.
3.2.2 Each data category shall
be coded with only a single color* code throughout the work environment.
3.3 Color* codes shall be consistent
with existing cultural conventions.
3.3.1 If cautions and warnings
are represented in the system, red shall be used only to code data related to a warning.
3.3.2 If cautions and warnings
are represented in the system, yellow (or amber) shall be used only to code data
related
to a caution.
3.3.3 If cautions and warnings
are represented in the system, green shall be used only to code data that have been
evaluated for
safety status
and
determined to be
in neither a caution
nor warning status.
3.3.4 Color* codes of operationally
critical data shall be consistent with existing conventions of related applications.
Other Important Considerations
4. Color shall be used sparingly
and only for specific operational purposes.
More about labeling with color.
More about grouping with color.
More about color and popout.
4.1 Color shall
not be used for decorative purposes.
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