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INTRODUCTION TO COLOR GUIDELINES AND STANDARDS

On This Page:  • About Color Guidelines and Standards 


This section of the website includes several kinds of information about color guidelines and standards:

Generic Guidelines and Standards Back to the top of the page.

Specific color guidelines and standards all differ with respect to the exact wording of their requirements, but the graphic problems that they address have a lot of overlap. Most fall into three general categories: discrimination and identification; luminance contrast; and general problems of color design.

These pages include our generic restatements of specific color guidelines and standards that we have reviewed, with illustrations and links to the related information in our website:
Guidelines about Discrimination and Identification of Colors
Guidelines about Luminance Contrast
Guidelines about General Color Design

About Color Guidelines and Standards Back to the top of the page.

In this section we briefly discuss some of the reasons why we have guidelines and standards. We also discuss and illustrate some problems of guidelines and standards as a means for assurance of quality of color usage, and suggest some research directions toward solving the problems.

Specific Color Guidelines and Standards Back to the top of the page.

This page includes a listing of aerospace and non-aerospace guidelines and standards that include color usage issues.
Specific Color Usage Guidelines

ABOUT COLOR GUIDELINES AND STANDARDS Back to the top of the page.

Why do we need Color Guidelines and Standards?

The consequences of poor color design are minimal in some applications (e.g., personal webpages), but in others the consequences can be life-threatening (e.g., flight critical displays in cockpits, air traffic control displays, launch-control displays). When poor design has important costs, the community needs some means of assuring sufficient usability and conformity to conventions.

The only reliable way to assure quality of color design is to ensure that human factors engineering is properly integrated into the design, development and testing of the product that gets deployed. This requires that:

- adequate specialized color and human factors expertise is used throughout the design and testing of the application
- those experts are given adequate design authority, and
- resources (time and money) for design and testing are sufficient in spite of (nearly inevitable) budget problems and schedule delays.

In this process color guidelines can provide the human factors professionals with a checklist of the important usability concerns related to color. They can also be used to focus interactions with color consultants.

For applications that involve public safety there is sometimes another role for standards. Standards can represent community agreement on uniform practices where they are needed. Universal use of green, yellow or amber, and red to label safety status, for example, allows users to understand their meaning in multiple environments with minimal need for training.

Proper integration of human factors expertise has not happened on some projects, for a variety of cultural and practical reasons. In lieu of that expensive process, color guidelines and standards are sometimes expected to provide a human factors shortcut, i.e., to allow graphics developers and design reviewers with limited knowledge of applied color science to avoid serious mistakes in color design.

That's too much to expect from any document, regardless of size and quality. Color perception is complicated. Perception of even simple patterns in the laboratory is only partly understood by color scientists. Color perception in natural work environments is far more complicated and less understood, and information displays continue to get more complex. It's unreasonable to expect that any short training course or guidelines document can replace years of specialized professional training and experience in applied color perception, color science and color design.

The Status of Existing Color Guidelines and Standards

The degree of difficulty in getting effective colors for information display depends on the complexity of the graphics. Until recently most data displays in military and domestic command and control applications were very simple. When display quality, computational power, and communication bandwidth were expensive and scarce, the displays were usually limited to stroke and alphanumeric graphics on uniform backgrounds. For such simple displays it may be possible to describe most of the likely serious color design errors with a reasonably compact set of standards.

This situation has changed dramatically over the past several years. Inexpensive display systems are now capable of routinely computing, transmitting, and displaying graphics as complicated as dynamic maps, photos, and video. Products with advanced graphics are now commonplace in office and home environments. These capabilities are starting to appear in command and control applications--in cars, planes and industrial control settings where public safety is an issue.

To safely exploit the full potential of these new capabilities we will need to adjust our approach to color standards. Conventional color standards are limited with respect to complicated graphics. Most suffer from either vagueness or over-restriction:

Some set desirable usability goals but are too abstract to provide useful guidance to designers with limited applied color training and experience.

For example:

The contrast between text and its background shall be sufficiently high to ensure readability of the text.
[Source: DOD HCISG V2.0, 1992] FAA HFDS, p 8-61.

"...In all cases the luminance contrast and/or color differences between all symbols, characters, lines, or all backgrounds shall be sufficient to preclude confusion or ambiguity as to information content of any displayed information."
Society of Automotive Engineers, AS8034 Minimum Performance Standards for Airborne Multipurpose Electronic Displays, SAE, Warrendale, Pennsylvania: 1993, p. 7.

These "performance-based" guidelines set excellent goals, but how are they to be achieved?

Other standards place constraints on specific graphic elements. These often set parametric requirements that can be verified by eye or instrument.

For example:

The minimum level of luminance for characters on a VDT, regardless of wavelength, shall be 70 cd per m2 (20 f-L).
NASA-STD-3000/T, 9.4.2.3.3.9 Visual Display Terminal Design Requirements

Indicator Contrast - The luminance contrast within the indicator shall be at least 50.0 percent..
NASA-STD-3000/T, 9.4.2.3.3.9 Display Contrast Design Requirements

"An adequate contrast of at least 7:1 should be maintained between foreground and background colors to enhance color perception and perceived image resolution."
[Source: CTA, 1996] FAA Human Factors Design Standard, p 8-61.

These are more easily verified, but are generally too simple and rigid to allow optimal design solutions in complicated graphic contexts. For example, if all graphic elements are required to have high luminance contrast the information density that can be achieved is unnecessarily limited by the resulting clutter. Another example is use of blue:

Pure blue shall not be used on a dark background for text, thin lines, or high resolution information. [Source: DOE-HFAC 1, 1992] FAA Human Factors Design Standard, p 8-58

8.6.2.2.7 Blue. Blue should not be used as the foreground color if resolution of fine details is required. [Source: DOD HCISG V2.0, 1992] FAA Human Factors Design Standard, p 8-57.

Two areas display blue text on black background and black text on blue. In both cases the smallest font-sizes are hard to read.

The blue/black combinations in the two panels above are difficult to read, especially at the smallest sizes.

Two areas display blue text on white background and white text on blue. In both cases the smallest font-sizes can be easily read.

When there is sufficient luminance contrast, however, as in the above blue/white panels, blue is a usable label color even at the smallest font sizes. There are also several other ways to make blue usable as a label in complex graphics.
More about using blue.

Possible Improvements

Guidelines and standards cannot replace properly trained and experienced human factors experts. Nevertheless, they might contribute to better design if the above limitations could be overcome.

One possible answer is to state the requirements in terms of the performance goals (e.g., legibility, discriminability, recognition), but then to go on to provide standard advice and methods for meeting the goals. It's a topic for research at this point whether and how this second part might be achieved.

One possible approach would be to construct a hierarchy of guidelines, beginning with high-level performance goals at the top level and proceeding down to more specific guidelines about graphic elements. We have developed a prototype hierarchy here:
Hierarchy of Color Usage Guidelines and Standards

This website is part of a project investigating how such a system of quality assurance might be developed. The site is not itself intended to be a substitute for a standards document but to explore and demonstrate potential of web resources that might eventually be used in such a site.

By exploiting the capabilities of the web it may be possible to state a requirement in the form of a performance goal, demonstrate successful and unsuccessful examples, and point designers to information about related color science and color design that could help them find a solution for their own specific application.


Related Topics:
go to this page
Discrimination and Identification Color Guidelines
go to this page Luminance Contrast Color Guidelines
go to this page
General Design Color Guidelines
go to this page
Specific Color Usage Guidelines



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