Transcript Lec3a Accessibility

Introduction to Accessibility
©2006 IBM Corporation
Learning objectives
By the end of this lecture, you should be able to:
Define accessibility and explain why accessibility is important
Describe accessibility regulations
Define assistive technology
Identify different disability types
Explain checklist items from accessibility guidelines
Locate accessibility resources
©2006 IBM Corporation
What is accessibility and why is it important?
©2006 IBM Corporation
What is accessibility?
Accessibility is successful access to information and use of information
technology by people who have disabilities or varying levels of physical
ability.
Accessibility involves designing or modifying equipment, hardware, or
software to allow access by people with disabilities.
©2006 IBM Corporation
Accessibility is about all of us.
World population:
Worldwide number disabled:
United States population:
United States number disabled:
6+ Billion
~1 Billion (16%)
281 Million
54 Million (19%)
Source: Population Reference Bureau, United Nations and. Forrester Study Commissioned by Microsoft
Physical Disabilities
Other conditions that inhibit I T use
Disabled population
16% of world
population is disabled
Aging
By 2010, 60% of US population
will be over the age of 35
Poor hearing
Mobility
Deaf
Blind
Failing vision
Nonnative speakers
Temporary disabilities
In the US, 17.9M people
speak a language
other than English at home
Everyday situations disable
certain senses temporarily
Noisy environments
(hearing)
Driving
(sight)
Color blind
Accessibility affects many people, especially with the growing need to
embrace aging workforces, customers, and citizens.
©2006 IBM Corporation
Serving end users better
Technologies developed for disabled people are useful to the aging and
multicultural populations.
Nonnative speakers with partial fluency can benefit from
seeing captions in real time, as a person speaks.
• Speech-to-text technology can give a competitive advantage to
organizations with audiences whose preferred language differs from
the spoken language.
• Serving people who are not native speakers can open new markets
or expand existing market share.
As people age, hearing and eyesight often diminish.
• Technologies designed to assist low vision and hard of hearing
people can give a competitive advantage to organizations with older
customers or an aging workforce.
• As an aging population, the “baby boomers” in particular have
significant disposable income, retirement investments, and
insurance needs.
©2006 IBM Corporation
Example of user experience with slight visual impairment
Example of 20-year-old user who has 20/20 vision.
Example of 50-year-old user who has 80% of original
vision and slight colorblindness.
©2006 IBM Corporation
Standards and legislation appearing worldwide
Canada
Canadian Human Rights Act
Ontarians with Disabilities Act – 2001
Common Look & Feel Web guidelines – 2001
United States
Section 508 of Rehabilitation Act requires federal
agencies to purchase electronic and information
technology that is accessible to people with disabilities.
States are enacting similar legislation.
Europe
 Many countries have enacted legislation or national standards:
 UK – Web accessibility, 2002
 Germany – Barrier Free Decree, 2002
 Italy – ICT accessibility & government procurement, 2004
 Switzerland – Public sector Web accessibility, 2004
 European Union – Procurement of accessible I T, 2004
 Spain – Accessibility for computer platforms, 1998
 Ireland – I T accessibility guidelines, 2002
 Netherlands – Web accessibility, 2003
 Sweden – Guidelines for computer accessibility, 1998
China
Law of the PRC on the Protection of
Disabled Persons – Provisions on
employment, public services, transportation,
and legal sanctions, 1991
Japan
 JIS standards
Litigation and legal inquiries triggered by legislation in the
United States
State of Arkansas: New state accounting system built on SAP technology is
inaccessible to blind employees.
Commonwealth of Pennsylvania: Web portal inaccessible to blind. SAP software
is the source of the problem; IBM is providing integration services.
Metro Atlanta Mass Transit: Web site schedule and services inaccessible.
Southwest Airline: Reservations and ticketing are inaccessible.
Connecticut: Attorney General’s office investigates Web-based tax filing services.
Bank of America: inaccessible Web sites and A TMs.
America Online: Software incompatible with screen readers.
Australia / New Zealand
 Disability Discrimination Act passed – 1996
 Australian Bankers’ Association endorsed e-
commerce standards – 2000
 Australian Communications Industry Forum's
(ACIF) Guidelines – 2001
©2006 IBM Corporation
Accessibility laws and regulations: Impact on designers
©2006 IBM Corporation
Accessibility laws and regulations: Impact on designers.
Web Content Accessibility Guidelines (WCAG
1.0) Priority 2's
Impact to developer
Workaround supported in A T or
browsers
2.2 Background and foreground contrast
M
Yes
3.1 Use markup when appropriate (i.e., SMIL)
H
3.2 Validate markup
L
Yes
3.3 Use style sheets to control layout/presentation
H
Yes
3.4 Use relative sizes
H
Yes
3.5 Use heading levels in document structure
M
Yes
3.6 Use list markup correctly
M
3.7 Use quotation correctly
L
5.3 Don't use layout tables that don't linearize
H
5.4 Don't use table markup in layout tables
L
7.2 Avoid blinking
M
Yes
7.3 Avoid moving content
M
Yes
7.4 Don't auto refresh
M
Yes
7.5 Don't auto redirect
M
Yes
Yes
©2006 IBM Corporation
Accessibility laws and regulations: Impact on designers
Web Content Accessibility Guidelines (WCAG 1.0)
Priority 2's
Impact to
developer
Workaround supported in A T or
browsers
10.1 Don't spawn windows without notifying user
M
Yes
11.1 Use W3C technologies
H
Yes
11.2 Avoid deprecated W3C features
M
Yes
12.2 Describe purpose of frames
M
12.3 Divide information into groups
H
13.1 Clearly identify target of link
M
13.2 Add metadata
L
13.3 Add site map and TOC
L
13.4 Use consistent navigation
M
Yes
©2006 IBM Corporation
Assistive technologies
©2006 IBM Corporation
Assistive technologies
 Assistive technology (A T) is hardware or software that is used to increase, maintain,
or assist the functional capabilities of people with disabilities. In short, it can be any
device or technique that assists people in removing or reducing barriers and enhancing
their everyday life activities. Examples of assistive technology include:
•
Screen readers, which are applications that speak screen information to people
who are blind
•
Screen magnifiers, which are are software that enlarges information on the
screen for people with low vision
•
Closed captioning, which displays the text version of the audio for people who are
deaf or hard of hearing
•
Special keyboards and input devices that assist people with limited hand use or
mobility impairments
©2006 IBM Corporation
Accessibility and assistive technology
 Accessibility: Attribute of information technology that allows it to be used by people with varying abilities
 Assistive Technology: Specialized I T that allows a user with a disability to access information technology
Inaccessible IT
Static font &
color
Requires
mouse
Graphics
only
Hard to reach
controls &
latches
Assistive Technology
Accessible IT
Assistive Technology
Font & color
settings
Screen readers
Screen readers
Magnifiers
Mouse is
optional
Magnifiers
Speech
recognition
Text with
graphics
Speech
recognition
Special
keyboards &
switches
Easy to reach
latches &
controls
Special
keyboards &
switches
Standards and APIs: MSAA, JAAPI,
standard windows controls
©2006 IBM Corporation
Understanding the impact of disabilities on an I T user
©2006 IBM Corporation
Vision
Issues: Cannot use the mouse for input, cannot see the screen, or
might need magnification and color contrast
Assistive Technology:
 Screen readers
 Braille displays
 Screen magnifiers
©2006 IBM Corporation
Blind users must use a screen reader and the keyboard.
User presses Alt key to access menu.
"File
submenu
press F"
User presses right arrow key.
The menu must be coded in a
standard way so that the screen
reader understands and can
convey the information to the user.
"Edit
submenu
press E"
©2006 IBM Corporation
Users with low vision need enlargeable fonts and high-contrast settings.
Font Size
Low Contrast
Larger font size
Even larger
font size
High Contrast
Large fonts and high contrast
A screen magnifier is needed when user needs go beyond operating system capabilities.
©2006 IBM Corporation
Color deficiency
Color-deficient users need more than color differences.
Green signals a server is online.
Red signals a server is offline.
The color blind user sees one color.
©2006 IBM Corporation
Color deficiency (continued)
It is okay to use color, as long as
color is not the only way to
convey information.
©2006 IBM Corporation
Hearing
Issues: Cannot hear audio, video, system alerts, or alarms
Assistive Technology:
 Closed captioning
 Transcripts
 ShowSounds
Four score and seven
years ago, our fathers…
©2006 IBM Corporation
Mobility
Issues: Limited or no use of hands, limited range, speed, and
strength
Assistive Technology:
 Alternate input (for example, voice)
 Access keys
 Latches that are easy to reach and
manipulate
©2006 IBM Corporation
Cognitive
Issues: Difficulty reading and comprehending information, difficulty
writing
Assistive Technology:
 Spell checkers
 Word prediction aids
 Reading and writing comprehension
aids
©2006 IBM Corporation
Accessibility checklists
©2006 IBM Corporation
Text equivalents for images, audio, and multimedia are key for Web checklist.
IBM Web Accessibility Checklist:
http://www-306.ibm.com/able/guidelines/web/accessweb.html
Text equivalents




Accessible interfaces
 Scripts must be keyboard accessible.
 Applets and plug-ins must meet software (or Java TM) accessibility checklist.
 Forms must be usable with assistive technology.
Skip navigation
 Provide a method for allowing the user to skip over navigation links to the main content.
Frames
 Provide a title for each frame element and frame page. Provide accessible source for
each frame.
Tables
 Use TH to mark up row and column header in data tables. Associate data cells with
header cells in complex data tables.
CSS (Cascading Style Sheets)
 Pages should be readable without requiring associated style sheets.
Color and Contrast
 Ensure all information conveyed with color is also conveyed in the absence of color.
Blinking, Flickering
 Avoid causing content to blink, move, or flicker.
Timed Responses
 Functions that have a time limit on the user's response must provide a way for the user
to ask for more time.
Text-only Page
 If accessibility cannot be achieved any other way, provide a text-only version of the
page.
Images and animations
Image maps
Graphs and charts
Audio and multimedia
©2006 IBM Corporation
Software requirements drive the way that code is implemented.
IBM Software Checklist:
www.ibm.com/able/softwarecheck.html
Keyboard Access
Provide keyboard equivalents for all actions.
Do not interfere with keyboard accessibility features built into the operating systems.
Object Information
Provide visual keyboard focus programmatically exposed to assistive technology.
Provide semantic information about user interface objects, including text for images.
Associate labels with controls, objects, icons, and images. Use images consistently.
Electronic forms must be usable with assistive technology.
Sounds and
Multimedia
Provide an option to display a visual cue for all audio alerts.
Provide accessible alternatives to significant audio and video.
Provide an option to adjust the volume.
Display
Provide text through standard system function calls or through an API that supports
interaction with assistive technology.
Use color as an enhancement, not as the only way to convey information.
Support system settings for high contrast for all user interface controls and client
area content.
When color customization is supported, provide a variety of color selections capable
of producing a range of contrast levels.
Inherit system settings for font, font size, and color for all user interface controls.
Provide an option to display animation in a non-animated presentation mode.
Timing
Provide an option to adjust the response times on timed instructions or allow the
instructions to persist.
Avoid the use of blinking text, objects, or other elements.
©2006 IBM Corporation
Documentation and support services are also covered; testing is required.
Documentation
Provide documentation in an accessible format.
Provide documentation on all accessibility features, including
keyboard access.
Support
Support services must accommodate the communication
needs of end users with disabilities.
Test
Verify accessibility using available tools:
- Assessment tools
- Assistive technology
- Manual verification for some items
©2006 IBM Corporation
A closer look at some Web coding techniques
©2006 IBM Corporation
Common Web accessibility issues
Web feature
Accessibility issue
Images
 Screen readers cannot read images without text equivalents.
 If null alt text is used for important links, the links are skipped and
the site is not accessible – even though it might pass an
accessibility checker.
Navigation
 Screen readers read Web pages sequentially.
 If Web sites that use frames do not have meaningful frame titles,
users cannot easily move to the content they want to read.
 If Web sites do not use frames, users must listen to all navigation
links unless a “skip to main” link has been added.
Data tables
 Screen readers cannot read row and column headings if the
headings have not been coded properly by the Web developer.
 Missing header labels make the table impossible to understand.
Forms
 Screen readers cannot read text labels on form elements if the
labels have not been coded properly by the Web developer.
©2006 IBM Corporation
Provide a text equivalent for every non-text element.
Alternate text (alt text)
•
Use alt=“text description” to provide text equivalents for images, graphs, charts.
•
Use null alt text (alt=“”) if images are unimportant or redundant.
•
Do not use alt=“” for image links unless the links are redundant.
•
Do not use alt=“ ” to implement null alt text.
•
Accessibility checkers check for the presence of alt=“text” or alt=“”.
Add alt text for all image links (input type=“image”).
Correct alt text for spacer images:
<img src= “spacer.gif” alt=“”>
<img src=“sam.gif”
alt=“Sam”>
Incorrect alt text:
<img src=“spacer.gif” alt=“spacer.gif”>
Correct alt text:
<input type=“image”
name=“Go” src=go.gif alt=“Go”>
Incorrect use of null alt text:
<input ytpe=“image”
Name=“Go” src=“go.gif alt=“”>
©2006 IBM Corporation
Provide a method to skip repetitive navigation links.
Provide a way to skip over navigation links to quickly get to main content.
•
Screen readers read Web pages sequentially, so users have to listen to all navigation links on the
page before they hear the main content.
•
A “skip to main” link enables screen reader users to skip navigation links on every page.
Correct coding for skip link using an image link:
<a href="#navskip">
<img src="http://spacer.gif.gif" alt="skip to main content" width="10" height="33" border="0">
</a>
…
<a name="navskip"></a>
<p>This is the main content on the page.</p>
Skip navigation links cannot be tested using checking tools. You must
listen to the Web page with assistive technology to hear the link and verify
that it works.
©2006 IBM Corporation
Give frames names that facilitate frame identification and navigation.
Provide a meaningful title attribute for each FRAME element.
•
Meaningful titles (for example, “Main Content”, “Navigation”, or ”Logo”) aid navigation of the Web
site.
•
Accessibility checkers check for the existence of the Frame title attribute; they do not check
whether the title is meaningful.
Correct coding for FRAME elements:
<frame title=“Navigation” src=“bp_left.html">
<frame title=“Logo” name=“top” src=“bp_header.html">
<frame title=“Main Content” src=“maincontent.html">
Incorrect coding for FRAME elements:
<frame src=“bp_left.html">
<frame name="top" src=“bp_header.html“>
<frame title="body_center" src=“maincontent.html">
©2006 IBM Corporation
Screen readers read frame titles.
 Use the screen reader command to list the frames on the page.
 Select the frame you want to read.
 Accessible frame titles:
 Inaccessible frame titles:
©2006 IBM Corporation
Use forms to allow people using A T to access the functionality required to
complete and submit the form.
Most form elements (for example, text fields, checkboxes, and radio
buttons) require explicit labels so the elements can be read by assistive
technology.
•
Associate text labels using the LABEL element and the for attribute.
•
Proximity is not sufficient to help assistive technology “see” field labels.
•
Accessibility checkers check for the presence of the LABEL element.
Correct coding of a text field for accessibility:
•
<label for=“search”> Search</label><br> <input name=“yourname” id=“search”>
Incorrect coding of a text field for accessibility:
•
Missing LABEL element: Search<br> <input name=“yourname”>
•
Missing id tag: <label for=“search”> Search</label> <br> <input name=“yourname”>
•
Incorrect id tag: <label for=“search”>Search</label> <br> <input name=“yourname” id=“mine”>
•
Implicit LABEL: <label>Search</label><br> <input name=“yourname”>
©2006 IBM Corporation
Screen readers read form labels.
 Locator feature – tells where am I?
Text entry
Labeled Search for
Form 1
At 28% of page
 List of links
 Controls reading with arrow keys
Search for [Text]
 Read title attribute
©2006 IBM Corporation
Define row and column headers for data tables.
Row and column headers must be defined so they can be spoken.
•
Use the TH element to mark up heading cells.
•
Use the scope attribute to identify row or column headings.
•
Use the headers and id attribute to identify row or column headings on complex tables that
use rowspan or colspan.
•
Accessibility checkers identify “possible” errors for tables because distinguishing between
data and layout tables is difficult.
The CAPTION element associates a title with the table.*
•
<caption>Computer Science Job Openings - November 2005</caption>
The summary attribute provides additional information about the table.*
•
<table summary="Table that summarizes federal job openings by date">
*Recommended technique, not required by Section 508 guidelines.
©2006 IBM Corporation
Identify row and column headers using the scope attribute.
Inaccessible table headers
Accessible table headers using scope
<tr>
<td>&nbsp;</td>
<td>Percentage with any disability</td>
<td>Number with any disability<td></tr>
<tr>
<td>Population 5-15 years</td>
<td>5.8</td>
<td>2,614,919</td></tr>
<tr>
<td>Population 16-64 years</td>
<td>18.6</td>
<td>33,153,211</td></tr>
……
<tr>
<td>&nbsp;</td>
<th scope=“col”>Percentage with any disability</th>
<th scope=“col”>Number with any disability</th></tr>
<tr>
<th scope=“row”>Population 5-15 years</th>
<td>5.8</td>
<td>2,614,919</td>
<tr>
<th scope=“row”>Population 16-64 years</th>
<td>18.6</td>
<td>13,978,118</td></tr>
……
©2006 IBM Corporation
Identify row and column headers using headers / id attributes.
Inaccessible table headers:
Accessible table headers using headers tag
<table summary=“Job openings by position>
<caption=“Technical Job Openings as of Nov 1, 2003”
<tr>
<td>Job Position</td> <td> Level</td>
<td>Location</td> <td>Agency</td></tr>
…….
<tr>
<td>Computer Scientist</td>
<td>GS-17</td>
<td>US-MS-Vicksburg</td>
<td>Army Research Lab</tr>
<tr><td>Army Corps of Engineers</td></tr>
<tr>
<td>US-MD-Prince George County</td>
<td>Army Research Lab</td></tr>
……
<th headers=“col1” id=“compsci” >Computer Scientist</th>
<th headers=“col2” id=“gs17” >GS-17</th>
<td headers=“compsci gs17 col3”>US-MS-VicksBurg</td>
<td headers=“compsci gs17 col4”>Army Research
Lab</td></tr>
<tr>
<td headers=“compsci gs17 col4”>Army Corps of
Engineers</td></tr>
……
<table summary=“Job openings by position>
<caption=“Technical Job Openings as of Nov 1, 2003”
<tr>
<th id=“col1”>Job Position</th> <th id=“col2”>Level</th>
<th id=“col3”>Location</th> <th id=“col4”>Agency</th></tr>
…..
<tr>
©2006 IBM Corporation
Screen readers read table headers.
 Table Jump reading
•
Reads the CAPTION element, which gives your table a title.
•
Reads the summary attribute of the TABLE element, which describes the overall structure of
a table.
 Table Navigation reading
•
Reads table headers.
•
Use TH to identify row and column headers for simple data tables. Use the scope attribute
on TH cells, if needed, to further clarify header and data cell relationships.
•
Use the headers attribute on data cells and the id attribute on header cells to identify
headers for complex data tables.
©2006 IBM Corporation
Listening to table headers with a screen reader
 Listening to the table without headers – response varies based on A T used
Matriculated Students. College of Education. 523
or
Matriculated Students. Undergraduate. 523
or
Matriculated Students. College of Education. Undergraduate. 523
 Listening to the table with headers – consistent and correct results
Matriculated Students. In state. College of Education. Undergraduate. 523
©2006 IBM Corporation
Summary of Web accessibility techniques
Web feature
Accessibility technique
Images
Use alt text for important images (alt=“your text”).
Use null alt text for unimportant or redundant images (alt=“”).
Navigation
Use a visible or invisible link to skip to main content.
Use the frame title attribute to add a meaningful name to your frame.
Data tables
 Use the TH element to identify row and column headers.
 Use headers and id attributes to identify row and column headers in
complex tables.
 Use the scope attribute on tables that don’t use rowspan or colspan.
Forms
Use the LABEL element to associate text labels with form elements.
©2006 IBM Corporation
Additional resources for learning about accessibility
IBM Human Ability and Accessibility Center
•http://www.ibm.com/able
IBM Human Ability and Accessibility Checklists and Techniques
•http://www.ibm.com/able/guidelines
IBM Home Page Reader
•Test instructions: http://www.ibm.com/able/guidelines/web/webhprtest.html
•Trial Download: http://www.ibm.com/able/solution_offerings/hpr.html
Guide to Section 508 Standards for Electronic and Information Technology
•http://www.access-board.gov/sec508/guide/
Web accessibility tutorials
•http://www.jimthatcher.com/webcourse1.htm
•http://www.webaim.org
•http://www.section508.gov
©2006 IBM Corporation