Die ETH an der 8. WWW-Konferenz in Toronto: Accessibility

Präsentation zum Thema: "Die ETH an der 8. WWW-Konferenz in Toronto: Accessibility"—  Präsentation transkript:

1 Die ETH an der 8. WWW-Konferenz in Toronto: Accessibility
Jakob Lindenmeyer Web Office der ETH Zürich Im Mai 1999 besuchte ich zusammen mit Reto & Roberto die 8. WWW-Konferenz in Toronto. Zusammen mit Reto hatte ich dort eine Präsentation zum Thema Accessibility und in meinem Teil werde ich hauptsächlich auf diese aktive Teilnahme der ETH an der WWW-Konferenz und dem Echo, das dadurch ausgelöst wurde, eingehen. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

2 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Accessibility “Zugänglichkeit” definiert sich dadurch, wie einfach ein Dokument auf dem Web durch einen Empfänger “verwendet” werden kann. Je höher die Anforderungen, desto schlechter ist das Dokument zugänglich. Anforderungen beinhalten die Fähigkeit der benötigten Hard- & Software sowie auch die Fähigkeit der Person, welche versucht die in einem Dokument zur Verfügung gestellte Information zu verwenden. Accessibility is defined as how easy a document on the web can be "used" by a client. The higher the requirements are, the less accessible a document is. Requirements include capabilities of the hardware and the software deployed as well as the physical capabilities of the person trying to use the information provided in a document. A document may include text, sound, graphics etc in any combination. This paper will concentrate on technical issues, non-technical issues such as language, intellectual capabilities of the person required to actually understand the contents etc are important as well, but beyond the scope of this work. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

3 TIP Accessibility «Accessibility benefits all!»
Accessibility ist nicht nur für Menschen mit Behinderungen wichtig! Accessibility unterstützt: Menschen mit Behinderungen Mobile Devices Internationalization Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

4 Problematik von «fettem» Design
«Low resource»-Geräte Mobile Devices Alte Software (Browser, Plug-In’s) Menschen mit Behinderungen Vorschriften, Richtlinien, Gesetze Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

5 «Low resource»-Geräte
Ältere Computer (z.B. JVM auf 486) Kleiner Bildschirm (z.B. VGA & Monochrom) => s Langsames 14.4 Kb/s-Modem Langsame Netzanbindung (Kein ISDN) Verbreitet bei Studierenden (beschränkte finanzielle Ressourcen) Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

6 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Mobile Devices Mobiltelefon (Bp: Nokia; s = ca. 2”) Handhelds (Screensize s = ca. 4 Zoll) Auto-Computer (mit Sprachausgabe für Fahrer) Browser in Armbanduhr (Screensize ca. 1 Zoll) Browser & CE in Haushaltsgeräten (z.B. Kaffeemaschine) CE-Browser => fB Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

7 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Alte Software z.B. Browser - Neue PC’s haben oft noch Internet Explorer 2.0 vorinstalliert. Browser an der ETH (Statistik) Plug-in’s (z.B. Shockwave, Quicktime, Realplayer) Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

8 Menschen mit Behinderungen
Laut Microsoft: 8%, WWW8: 10% Farbenblindheit (4 % aller Männer) Sehbehinderung (Grosse Schriften notwendig) Blindheit => Audio-Browser oder Braille Bewegungseinschränkung (Keyboard- bzw. Mouse-only Navigation) Taubheit (Alternativen für Audio-Dateien) 10% aller Menschen haben irgendeine Behinderung der obigen Art (nach WWW8) Tages-Anzeiger vom S. 61: "Auch Blinde wagen sich ins World Wide Web".URL: Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

9 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Poster Abstract: Tim Berners Lee - often referred to as the "father of the Web" - once said: "The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect". To underline this, the W3C has started the "Web Accessibility Initiative" (WAI) in But regardless of these activities, it seems to me, many designers of web pages do not care too much about accessibility. This poster tries to find out what influences accessibility of web pages. Research was performed on how the code generated by an authoring tool and the HTML -tags and attributes present in a document influence accessibility. In addition, the impact of the capabilities of the hardware and software deployed on the client side as well as potential disabilities of the person who actually tries to use the information was analyzed. This was done in our accessibility lab, where web pages were looked at with many different browsers on various hardware platforms. Based on the findings, a method was developed to measure accessibility of web pages and a list of recommendations to create documents that are accessible by virtually everyone was compiled. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

10 «Zugänglichkeit des Inhalts» c
Testen der Webseite mit verschiedenen Clients (Bp: ZKB) Wieviel Informationen erreicht man mit verschiedenen Browsern («content-accessibility» c) (Berücksichtigung der Fähigkeiten der verschiedenen Browser (fB)) To measure accessibility, web pages have been tested with different clients (see Example). An accessibility value in percent was calcula-ted depending on how much of the web pages actually could be used with each browser ("content-accessibility" c) and depending on each browsers capabilities (fB). Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

11 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Browser-Faktor fB(i) Many web sites depend on Java scripts or applets, but some browsers are not able to execute such scripts, including Microsoft Pocket Internet Explorer on Windows CE and most non-graphical browsers, such as Lynx or WebSpeak. Also, some people may have configured their browser to disallow the execution of any scripts locally for security reasons. fB(i) = Browser factor Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

12 «Text als Bild»-Faktor fi
Problematiken von Text als Bild: 1. Bilder skalieren nicht. 2. Bilder eignen sich nur für grafische Browser. 3. Bilder werden durch Suchmaschinen nicht indexiert. 4. Bilder verlangsamen den Transfer eines Dokuments. 5. Bilder sind schwieriger zu unterhalten. Text as images: 1. Images do not scale. 2. Images are good for graphical browsers only. 3. Images will not be indexed by search engines. 4. Images slow down the transfer of a document. 5. Images are more difficult to maintain. fI = "text as images"-factor: No: [1], Yes: [0.8] Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

13 Minimale Bildschirmbreite s
Fixe Attribute von Tabellen oder Frames können zu unzugänglichen Bereichen einer Webseite führen. Werte: z.B. VGA: Pixel XGA: 1024 Pixel Resolution of the screen: Some layouts depend on a minimal win-dow width. Fixed width attributes of tables or frames may lead to inaccessible parts of a document on screens with low resolution. s = minimal screen width of the web page in pixels. Heuristically 640 pixels (VGA) has been chosen as an acceptable screen width without loss of accessibility. The formula leads to a decrease of the accessibility by 10% if a minimal screen width of 1024 pixels (XGA) is required. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

14 «Fixierte Farbe»-Faktor fC
Anzahl der Farben: Je kleiner, desto schlechter unterscheidbar Fixierung der Farbschemata: Schwierigkeiten bei Farbwahrnehmung und Unterschiede bei Monitoren Number of colors: The lower the number of supported colors, the less distinguishable similar colors may become. Fixed color sche-mes: Some people have difficulties to see some particular colors or color combinations. In addition, colors appear different from monitor to monitor. fC = "fixed color"-factor: No: [1], Yes: [0.9] Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

15 Measuring Accessibility
To measure accessibility, web pages have been tested with different clients (see fig.1: Browsers). An accessibility value in percent was calculated depending on how much of the web pages actually could be used with each browser ("content-accessibility" c) and depending on each browsers capabilities (fB). Let: a = accessibility value in percentages c = content-accessibility: the information is: fully accessible: [100%], still useful: [67%], important information is missing: [33%], not accessible: [0%] fB = browser-factor: Fig.1: Browsers (1) fC= "fixed color scheme"-factor: No: [1], Yes: [0.9] fI = "text as images"-factor: No: [1], Yes: [0.8] s = minimal screen width of the web page in pixels. Heuristically 640 pixels (VGA) has been chosen as an acceptable screen width without loss of accessibility. The formula leads to a decrease of the accessibility by 10% if a minimal screen width of 1024 pixels (XGA) is required. then: see formula in slide Publikation unter: Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

16 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
Rangliste Complete list of results under: Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

17 ZKB mit Netscape Communicator 4.5
Bildschirmbreite = 640 Pixel Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

18 ZKB mit MS Pocket Internet Explorer
(Kein Java) Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

19 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
ZKB mit Lynx V 2.8 (Textbrowser) Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

20 Full Presentation under: www.weboffice.ethz.ch/eth-w4/
ZKB mit pw WebSpeak (Audio Browser) Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

21 W3C-Feedback Judy Brewer, Director of the Web Accessibility Initiative
Ian Jacobs, Editor of the WAI Guidelines Dave Raggett, Development of HTML Judy joined W3C in September 1997 as Director of the Web Accessibility Initiative (WAI) International Program Office. She coordinates five activities with respect to Web accessibility: data formats and protocols; guidelines for browsers, authoring tools and content creators; rating and certification tools; education and outreach; and research and advanced development Prior to joining W3C, Judy was Project Director for the Massachusetts Assistive Technology Partnership, a U.S. federally-funded project promoting access to assistive technology for people with disabilities. Judy has a background in applied linguistics, education, technical writing, management and disability advocacy. She chairs the Web Accessibility Initiative International Program Office Interest Group. Ian studied computer science in France after college (Yale), and worked at INRIA for about 5 years on a system called "Centaur", realized by the CROAP project. After a total of 7 years in France and Italy, he moved back to New York City in In March 1997, Ian began consulting for W3C as an editor, and has been working a variety of projects, including the three WAI Guidelines, the HTML 4.0 specification, the CSS 2.0 specification, and the W3C Process Document. Dave joined W3C in May 1995 on assignment from HP Labs. Dave has been involved with the development of HTML from the early days as well as setting up the IETF HTTP working group and helping to initiate work on VRML. He is the author of "Raggett on HTML4", his second book on HTML. Dave is currently involved in work on next generation style sheets, voice browsers, and easy ways to include math on the Web. He was educated in England and obtained his doctorate from the University of Oxford. Philipp is the Leader of the W3C Architecture Domain. He also leads the Synchronized Multimedia Activity of W3C. He served as editor of the W3C Recommendation SMIL, and as chair of the working group that developed SMIL. He also chaired W3C workshops on Real-Time Multimedia and the Web , Push Technology and Television and the Web . Philipp Hoschka, Leader of the W3C Architecture Domain. Editor of SMIL-spec. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

22 WAI Quick Tips Reference Card
 Handout Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

23 Deutsche Übersetzung der W3C-Quicktips
Liegt unter:  Handout Tips zur Entwicklung zugaenglicher Webseiten * Bilder und Animationen. Verwende das "ALT"-Attribut zur Beschreibung der Funktion aller visuellen Objekte. * Image maps. Benuetze Client-side "MAP" und Text fuer "Hotspots". * Multimedia. Biete Ueberschriften, Abschriften von Tondokumenten, Beschreibungen von Videosequenzen und alternative Versionen an fuer den Fall, dass nicht unterstuetzte Formate benutzt werden. * Hypertext-Verknuepfungen Verwende sinnvollen Text fuer Links. Vermeide z.B. "Hier klicken!". * Seitenorganisation. Verwende Titel, Listen und eine einheitliche Struktur. Setze nach Moeglichkeit CSS zur Steuerung des Layouts ein. * Grafiken. Biete Zusammenfassungen an oder verwende das "LONGDESC"-Attribut. * Skripte, Applets & Plug-ins. Stelle Alternativen zur Verfuegung fuer den Fall, dass gewisse Funktionen nicht unterstuetzt werden. * Frames. Kennzeichne Frames mit "TITLE" oder "NAME" Attributen. * Tabellen. Tabellen sollen auch zeilenweise gelesen verständlich sein. Fasse zusammen. Vermeide den Missbrauch von Tabellen fuer die Darstellung. * Ueberpruefung. Validiere den HTML-Code. Benuetze Validierungswerkzeuge und Textbrowser zur Ueberpruefung der Zugaenglichkeit. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

24 «Accessibility does not mean minimal page design; it means thoughtful page design!»
Web Content Accessibility Guidelines Als Abschluss hier noch ein Zitat aus den Accessibility-Richtlinien des WWW-Consortiums. «Accessibility does not mean minimal page design; it means thoughtful page design!» . Eine gut zugängliche Website muss also nicht langweilig oder aufändig zu entwickeln sein, sondern man muss sich einfach etwas überlegen, wenn man die Site designt. Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

25 Publikationen, Beilagen & Handouts zu dieser Präsentation
ETHZ Internet Richtlinien Paper-Abstract “Measuring Accessibility” Web Content Accessibility Guidelines WAI Quick Tips Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under:

26 Folien dieser Präsentation
sind erhältlich unter: Fragen & Diskussion Jakob Lindenmeyer, 9. Juni 1999 Full Presentation under: