Transcript Color Blindness

Web design for color blind users
Presented by
Rajalekshmy Usha
HCI assignment 4
12/11/2001
Color Blindness
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Hereditary genetic disorder
Afflicts 8 percent men and 0.5 percent
women
Most services and companies use no or less
consideration for this group. For example,
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some instructions say “press the red button”
Color coded pills
Red warning and green safety light on some
machines
Types of Color Blindness
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Red-Green Color Vision Deficiency:
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Most commonly referred to as “color vision
deficiency” since the sufferers are not entirely
blind to colors
Total Color Blindness:
Rare, but is present across all ethnic groups
 Two types:
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•Typical : complete failure to discriminate colors
•Atypical : low color sensitivity, only clear colors detected
Statistics and facts on color
blindness
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Approximately 10 million people in United States are blind
and visually impaired
At least 1.5 million blind and visually impaired Americans
use computers (source :American Foundation for Blind)
Males are more prone to color blindness
7 percent males and 0.4 percent females suffer from red-green
color blindness
A Simple Color Blind Test
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A normal person sees a
5 revealed among the
dots
A red-green color blind
person sees a 2 revealed
in the dot
How a normal person sees the world
How a person with red-green color
deficit sees the world
How a person with blue-yellow color
deficit sees the world
Web Design Analysis
Most of the current web designers give little or
no consideration for color blind users
 Not willing to sacrifice minor design elements
for the majority of the users
 However popular web sites are simple and not
overloaded with colors
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Examples of web-sites with poor
readability
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http://www.moviephone.com/
Light orange background in the left navigation
menu
 Different color links with green and orange which
blends in
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http://www.wired.com/:
garish colors
 too much even for normal users
 Red and green backgrounds are kept together
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Examples of web-sites with good
readability
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http://www.amazon.com/
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http://www.hotmail.com/
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Simple and elegant
Used distinct colors for menus, images etc
No red and green colors together
The butterfly icon may not be that distinct
http://www.whitehouse.gov/:
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Again simple and plain
but fonts on the menu tab could have been larger
My Goal for this Web Design
Make internet accessible to color blind users
 Provide an opportunity for web-designers,
system developers and for all society
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Acid Test on the readability of color
combination
-Represent worse-case scenario since the fonts are small and the
backgrounds are highly saturated
-Brightness of the font increases from top to bottom and
the brightness of the background increases from left to right
- I will use this color swatch for web designing
My web design guidelines for color
blind users
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Use ALT = ‘…’ text for all the images.
 Use JavaScript Mouse over events to describe the status
event description of all the images
Use blue, yellow, white and black to really distinguish items
Provide numerous links with a text version , if you cannot do
without graphics
Provide labels next to any colored indicators
Emphasize important with larger fonts, color highlight(proper
ones!) and outlining boxes
Provide visual cues like icons or arrows if there are no
underlining for text links
Click on the red button
Next
My web design guidelines for color
blind users - 2
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Provide strong contrast between background
and the foreground colors
Effective and non-effective
hue contrast is shown in
the picture alongside.
What are not allowed …
DON’T :
 Use red/purple/gray/brown/green next to or to the
A A A AA
top of red/purple/gray/brown/green
AAAAA
 Use various shades of one color
 Use single light bulb that changes color from red to
yellow or green to yellow under any circumstances
 Use colors in images to denote special areas, such as
bar charts, maps, and navigation bars
 Overload the web site with large number of visually
striking buttons, garish colors and extreme imageries.
hotel
(email icon - bad format! )
phone
water ( good format )
What are not allowed …2
DON’T :
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Use decorative , complicated or cursive fonts
• Roman typefaces are effective
• Decorative typefaces are not effective
• Condensed typefaces are not as effective
• Sans serif type faces are effective
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Extensive use of italics – oblique or condensed
•Upper and lowercase of a typeface is more readable
• Italics and bold types are not as effective
Interface Designs to be considered
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Give information feedback by giving instructions,
which refers to objects e.g. “press the button marked
“ON” or “wait for the light on the left”
Strive for consistency throughout while designing the
websites
Do regular usability testing – it provides opportunity
for revision and improvement
Compactness and branching factors of web page
Conclusions
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Black and white works best
Never solely rely on colors
Enhance each use with an image, shape, positioning
or text
Use bright colors – they are easiest to tell apart
Use the appropriate back ground so you can make
even the less safe color visible
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E.g. red against white, green against black, turquoise against
black, magenta against black.
Internet Resources for Web design
for Color Blind Users :
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www.firelily.com/opinions/thumb.html
http://www.firelily.com/opinions/color.html
www.vischeck.com
http://newmanservices.com/colorblind/default.asp
http://members.aol.com/nocolorvsn/color5.htm
http://www.visibone.com/colorblind/
http://trace.wisc.edu/world/web/