- From: Wendy A Chisholm <wendy@w3.org>
- Date: Wed, 03 May 2000 11:27:22 -0400
- To: "Leonard R. Kasday" <kasday@acm.org>, Peter Verhoeven <pav@oce.nl>, w3c-wai-er-ig@w3.org
After thinking about this more, we could discuss the following techniques that would help determine if a page is accessible to someone with low vision: 1. how to determine if an image has text. if it does have text suggest that the text become the alt-text, perhaps also suggest that the author use style sheets. 2. check the page for high contrast color combinations - see the color study done by the ATRC in Toronto for more info. http://snow.utoronto.ca/readtest 3. check images for high contrast color combinations - this requires determining the colors used in the image. 4. I'm not sure what automated technique to suggest for this one: 2.1 Ensure that all information conveyed with color is also available without color, for example from context or markup. [Priority 1] --wendy At 08:00 AM 5/3/00 , Wendy A Chisholm wrote: >I disagree with this suggestion. I believe the points that are being >discussed are a WCAG issue not a tool issue. Now is the prime time to >take these issues to the WCAG working group as they have begun thinking >about revising the guidelines - particularly to address cognitive and >learning disabilities and to generalize the checkpoints so that they are >less HTML specific. > >Also, I don't believe enough credit is being given to what WCAG already >addresses in regards to low vision. > >Here are some excerpts from WCAG 1.0: > >Content developers must consider these different situations during page >design. While there are several situations to consider, each accessible >design choice generally benefits several disability groups at once and the >Web community as a whole. For example, by using style sheets to control >font styles and eliminating the FONT element, HTML authors will have more >control over their pages, make those pages more accessible to people with >low vision, and by sharing the style sheets, will often shorten page >download times for all users. > >Content developers must consider these different situations during page >design. While there are several situations to consider, each accessible >design choice generally benefits several disability groups at once and the >Web community as a whole. For example, by using style sheets to control >font styles and eliminating the FONT element, HTML authors will have more >control over their pages, make those pages more accessible to people with >low vision, and by sharing the style sheets, will often shorten page >download times for all users. > >(from the rationale of Guideline 1) >This guideline emphasizes the importance of providing text equivalents of >non-text content (images, pre-recorded audio, video). The power of text >equivalents lies in their capacity to be rendered in ways that are >accessible to people from various disability groups using a variety of >technologies. Text can be readily output to speech synthesizers and >braille displays, and can be presented visually (in a variety of sizes) on >computer displays and paper. Synthesized speech is critical for >individuals who are blind and for many people with the reading >difficulties that often accompany cognitive disabilities, learning >disabilities, and deafness. Braille is essential for individuals who are >both deaf and blind, as well as many individuals whose only sensory >disability is blindness. Text displayed visually benefits users who are >deaf as well as the majority of Web users. > >Related Checkpoints: >2.1 Ensure that all information conveyed with color is also available >without color, for example from context or markup. [Priority 1] > >2.2 Ensure that foreground and background color combinations provide >sufficient contrast when viewed by someone having color deficits or when >viewed on a black and white screen. [Priority 2 for images, Priority 3 for >text]. > >3.1 When an appropriate markup language exists, use markup rather than >images to convey information. [Priority 2] >For example, use MathML to mark up mathematical equations, and style >sheets to format text and control layout. Also, avoid using images to >represent text -- use text and style sheets instead. Refer also to >guideline 6 and guideline 11. > >WAC note: if markup is used rather than images, text can be displayed >however the user chooses. the user can choose size, color, and font. > >3.3 Use style sheets to control layout and presentation. [Priority 2] >For example, use the CSS 'font' property instead of the HTML FONT element >to control font styles. > >WAC note: Again, this is giving control to the users. > >3.4 Use relative rather than absolute units in markup language attribute >values and style sheet property values. [Priority 2] >For example, in CSS, use 'em' or percentage lengths rather than 'pt' or >'cm', which are absolute units. If absolute units are used, validate that >the rendered content is usable (refer to the section on validation). > >WAC note: this gets at the issue that Len mentioned. If relative units >are used, when the font is increased the layout should adjust so that >there is not overlap. > >--wendy > >At 09:36 AM 5/2/00 , Leonard R. Kasday wrote: >>I'd suggest we add a discussion of partial sight/low vision to the face >>to face agenda to follow up on the points made by Peter. >> >>How about planning on an hour's worth after lunch on Thursday? We would >>of course to either omit things now in that slot or move them and omit others. >> >>Len >> >> >>At 09:36 AM 5/2/00 +0200, Peter Verhoeven wrote: >>>Hi, >>> >>>This is not the first time that I bring up this point, but because I got >>>less responce here a new try. >>> >>>The WAI often mentions numbers of people that having problems accessing >>>web pages of the Internet. I often read the number 10 million. Are those >>>10 million people blind? No, they are not blind at all. A lot of them >>>are sight impaired which is not the same. >>>In the "quick tips" I read only tips to make web pages accessible to >>>blind, or maybe to make web pages accessible by using Lynx? If I check >>>web pages with real accessibility problems for sight impaired with >>>Bobby, it tells me Congratulations your web page is Bobby Appoved. I >>>only need to do some manual checking, but all these checkpoints have >>>nothing to do with things like universal design and color contrast. >>> >>>A growing number of web pages are designed "system dependent" that >>>means, that if I don't have a special display resolution or font size >>>setting a lot of information on the web pages is outside my screen and >>>the only way to access is to track on bars. >>>Some web designers don't like trackbars and disable them, so it becomes >>>realy impossible to get some information on the page. But the page is >>>Bobby approved (Congratulations!). >>> >>>In the statistics from visitors to my web site The Screen Magnifiers >>>Homepage at http://www.magnifiers.org I see that 25% of my visitors have >>>a display resolution of 640x480. We as sight impaired use this >>>resolution often because the the text on hte screen is much lagere than >>>in a higher resolution and setting a high resolution means that you need >>>a more powerful system with more memory to let a screen magnifier >>>performs well. >>> >>>A lot of these problems occurs in table and frames constructions and >>>personaly I know it is often difficult to solve these problems also if >>>you specified a table width of 640. If an image inside the table is >>>larger than 640 or a word in a cell is larger the width of the table >>>increases. A lot of web designers don't want to use percentages for >>>defining table widh, because the lines of text becomes so long if >>>someone has set a high display resolution. The problem "long line" seems >>>to have a higher priority than "horizontal scrollbars". >>> >>>In my opinion a lot of these problems could be solved by the makers of >>>browsers. >>>In my opinion more attention is needed for accessibility problems that >>>partially sighted have? >>> >>>Regards Peter Verhoeven >> >>-- >>Leonard R. Kasday, Ph.D. >>Institute on Disabilities/UAP, and >>Department of Electrical Engineering >>Temple University >>423 Ritter Annex, Philadelphia, PA 19122 >> >>kasday@acm.org >>http://astro.temple.edu/~kasday >> >>(215) 204-2247 (voice) >>(800) 750-7428 (TTY) > >-- >wendy a chisholm >world wide web consortium >web accessibility initiative >madison, wi usa >tel: +1 608 663 6346 >/-- -- wendy a chisholm world wide web consortium web accessibility initiative madison, wi usa tel: +1 608 663 6346 /--
Received on Wednesday, 3 May 2000 11:31:48 UTC