Transcript Web pages and accessibility

Accessibility issues for
web authors
Library and Information Services
University of St Andrews
Structure
1. Definition: Accessibility
2. Legal requirement
3. How people access the web
4. Web Accessibility Initiative
5. Checking your web pages
6. Resources
1. Definition: Accessibility
 Technical aspects



hard- & software issues
different devices
internet connection
 Varying individual needs


people with disabilities
use of specialised software
2. Legal requirement
 SENDA (2001) and DDA (1995):

Responsible bodies must not treat a disabled
person less favourably than a non-disabled
person for reasons related to their disability
without justification

Responsible bodies will be required by law to
make reasonable adjustments to ensure that
a disabled person is not placed at a
substantial disadvantage.
3. How people access the web
 Visual disabilities
 Blindness, colour blindness, other visual impairments
 Physical disabilities
 Repetitive stress injury
 Hearing disabilities
 Deafness, hard of hearing
 Cognitive disabilities
 Dyslexia, attention deficit disorder, intellectual
impairments
 Neurological disabilities
 Seizure disorders, mental health problems
… among others.
3.1. Visual disabilities
3.1.1. Blindness
 Specialised software:
 Speech synthesisers, braille browsers
 Text-based browsers (Lynx)
 Possible use of “rapid browsing techniques”
 Potential problems include:
 Images without descriptive “alt tags”
 Tables that do not make sense when read serially, i.e.
in a “linearised” way
 Navigational features that rely on mouse, no keyboard
navigation
 Hyperlinks don’t use meaningful text
 Non-standard document formats
Use meaningful text for hyperlinks
(1/2)
 For more information on how to get to Paris,
please click here.
 Click here to download a map of the city
centre.
 To look at the 2003 statistics on tourism to
France, click here.
is turned into ...
Use meaningful text for hyperlinks
(2/2)
 click here
 Click here

click here
Use descriptive ALT tags
Context 1: as a simple graphic of an organisation’s logo
appearing on a web page.
alt=“ASPC logo”
Context 2: image is active link to the home page of a web
site.
alt=“Home”
Context 3: image might be used in a list of properties, as an
icon to indicate properties available through the ASPC.
Since the image contains an abbreviation, the alt text of
the image might now be
alt=“Ardcalloch Solicitor’s Property Centre”
Lynx
 Example web sites:


http://www.polarfle.com
http://arts.st-andrews.ac.uk
 Online lynx viewer:

http://www.delorie.com/web/lynxview.html
3.1.2. Colour blindness
 Lack of sensitivity to certain colours
 Possible use of personalised style sheets
 Potential problems include

Colour that is used as a unique marker to
emphasise text

E.g. “click the red button”
 Potential problems (cont.)

Inadequate contrast between text and
background
Certain colour combinations

No option to override default colours

Examples of colour deficits
 Protanope

one out of 100 males, “red-weakness”
 Deuteranope

five out of 100 males, “green-weakness”
 Tritanope

blue/yellow deficit
Colour perception (1/2)
Normal vision
Protanope
Deuteranope
Tritanope
Colour perception (1/2)
Normal vision
Protanope
Deuteranope
Tritanope
Other visual impairments
 Forms include: poor acuity, tunnel vision,
central field loss, clouded vision
 Specialised software:

Screen magnifyers, speech synthesisers
 Possible use of grayscale display
 Potential problems include:
 Absolute font sizes
 Inability to change colour settings
 Inconsistent layout that makes navigation difficult
 Centred display of items on screen
 Poor contrast
 Text presented as images
 Resolution of images conveying important information
is too low
 Depending on type and extend of disability, many of
the problems blind people encounter
3.2. Physical disabilities
3.2.1. Repetitive stress injury
 Happens when too much stress is placed on
a joint; same action is performed over and
over again
 Possible use of software that does not require
the use of a mouse
 Potential problems include:
 Web pages cannot be navigated using a
keyboard alone
3.3. Hearing disabilities
3.3.1. Deafness
 Sign language may be “first language”, i.e.
possible problems reading written language
fluently
 Potential problems include:



Lack of captions or transcriptions of audio
content
Lack of content-related images
Lack of clear and simple language
3.3.2. Hard of hearing
 People with mild or moderate hearing
impairments
 Possible problems include:

Lack of captions or transcripts for audio
content
3.4. Cognitive disabilities
3.4.1. Dyslexia
 Possible difficulty processing written language or
images when read visually, or spoken language when
heard, or numbers when read visually or heard
 Possible use of speech synthesisers
 Possible problems include:
 Lack of alternative text that can be converted to audio
to supplement visuals
 Justified text
 Mixture of fonts & font sizes
 Possible problems (cont.):




Extensive use of ALL CAPS
Words split across lines
Large chunks of text
No white space between paragraphs
3.4.2. Attention deficit disorder
 Difficulty focusing on information
 Possible problems include:


Distracting visual or audio elements that
cannot be turned off
Lack of clear and consistent organisation of
web sites
3.4.3. Intellectual impairments
 May learn more slowly, difficulty understand
complex concepts
 Possible problems include:



Use of unnecessarily complex language
Lack of graphics
Lack of clear and consistent organisation
3.5. Neurological disabilities
3.5.1. Seizure disorders
 E.g. photosensitive epilepsy
 Avoid content that flickers at a frequency
of between 2 and 59Hz
 Possible problems:

Animated, flickering or flashing content
3.5.2. Mental health problems
 May have difficulty focusing on information,
experience blurred vision or hand tremors
owing to side effects of medication
 Possible problems include:


Distracting audio or visual elements that
cannot be turned off
Use of absolute font sizes
3.6. Complexities
 Multiple disabilities:
 e.g. deaf & blind
 Conflicting needs of people with different disabilities
 e.g.: People with cognitive disabilities may require
graphical rather than textual presentation; blind people
rely on text.
 You can’t get it right for everyone. Therefore,
make sure that people can override your settings!
4. The Web Accessibility Initiative
(WAI)
http://www.w3.org/WAI/
 Guidelines:



Web Content Accessibility Guidelines 1.0
(WCAG 1.0, http://www.w3.org/TR/WCAG)
Authoring Tool Accessibility Guidelines 1.0
User Agent Accessibility Guidelines 1.0
Web Content Accessibility
Guidelines 1.0
 3 Priorities (Levels of compliance):
 Priority 1 (A-compliant):
 Criteria a web developer must satisfy
 Basic requirement for some groups to be able to
access web documents
 Priority 2 (AA-compliant):
 Criteria a web developer should satisfy
 Removes significant barriers to accessing web
documents
 Priority 3 (AAA-compliant):
 Criteria a web developer may satisfy
 Improves access to web documents
5. Checking your web pages
 Use validators:
 HTML validator: http://validator.w3.org
 Bobby:
http://bobby.watchfire.com/bobby/html/en/index.jsp
 Cynthia SaysTM:
http://www.cynthiasays.com/Default.asp
 Apply visual checks:
 Use of colours
 Use of fonts (font-family, relative sizes, …)
 Meaningful ALT tags
 …
 Check your web pages in various browsers
6. Resources
 Vischeck Colour vision simulator:




http://www.vischeck.com/examples/
W3C: validators and technical standards:
http://www.w3.org
Teachability: http://www.Teachability.strath.ac.uk
Techdis http://www.techdis.ac.uk
SENDA/DDA
http://www.legislation.hmso.gov.uk/acts/acts2001/20010010.htm
 JISC legal
http://www.jisclegal.ac.uk/publications/legalimplicationsDDA.htm
… and many more
Accessibility issues for
web authors
Library and Information Services
University of St Andrews