- From: Wendy A Chisholm <wendy@w3.org>
- Date: Mon, 08 Dec 2003 13:29:46 -0500
- To: w3c-wai-gl@w3.org
IRC log: http://www.w3.org/2003/12/04-wai-wcag-irc.html Review draft: http://www.w3.org/WAI/GL/2003/11/18-f2f-review-draft.html Present: Mat Mirabella, Michael Craddock, Doyle Burnett, Yvette Hoitink, Wendy Chisholm, Mike Barta, Ben Caldwell, Loretta Guarino Reid, Jason White, Matt May, Gregg Vanderheiden, Andi Snow-Weaver, Avi Arditti, Bengt Farre, Roberto Scano, Kerstin Goldsmith Regrets: Cynthia Shelly, David Donovan, Roberto Castaldo, Patrizia Bertini, Maurizio Vittoria Summary of action items: 1. action: editors add an example to the unicode guideline about hard to read font. due to UAAG the UA could swap font. 2. action: wendy, loretta, mat, gregg, doyle work on visual contrast guideline(s) Topic 1: Guideline 1.6 in visual presentations, make it easy to distinguish words and images. http://www.w3.org/WAI/GL/2003/11/18-f2f-review-draft.html#visual-contrast Several issues with this guideline and its success criteria 1. "easy" is subjective (although this is a guideline not success criterion and thus does not have the same testability issues) 2. level 2 sc (proposed wording): when displaying text against a background, provide a method to make the contrast between foreground and background greater than ____ as measured by ____. This success criterion could be testable, if we can fill in the blanks. 3. Is "provide a method" needed in the success criterion? or leave it as "...make the contrast between..." or "it must be possible for the viewer to obtain contrast..." 4. "when displaying text against background" talking about text or raster image of text? The 4th point became the primary discussion in order to clarify the goal of this Guideline and success criteria. For example, if the user is able to select text (to create contrast via highlight mechanisms), does this satisfy the guideline? The user could then copy and paste the text into another application to read it. Does selecting text get rid of the background image? Using selection is not what is intended, instead the user should be able to change colors and/or turn off background images (in HTML). In SVG, Flash and PDF, what are the requirements? Perhaps we say at level 3 - be readable (by default). level 2 - user can make it readable. This raises other questions such as: 1. Can an author do anything that would prevent author from turning off background image? 2. Do we assume UAAG is implemented and therefore can assume that the ability to change settings is available? WCAG 1.0 has "until user agents." in the past we've said, "user agents should do X, but they don't so authors have to do y." at some point it would be ideal to say "these are the author responsibilities (x,y,z) and these are user agent responsibilities (a,b,c)." Ideal to constrain author responsibilities as much as possible to prevent us from getting lost in the relationships. Even if this explanatory, it should be able to help us reach decisions and help us show others how reached them. Returning to the SVG/Flash discussion, there were several questions about pulling the text from the markup/file format. We need to do research in this area. Regardless, we want to describe how content should behave without knowing what generated the content. Thus, at level 2: material should either have contrast or have a way to create that condition. Discussing how it should behave, we wondered about: 1. What about dropcaps? frillwork makes it unreadable to person with low vision. We don't say anything about fonts being recognizable. i.e., i can use wingdings and that's a font. in svg i can have a word, change first letter into something that is not easily recognizable as a character. it can have background and other features. it can be ornate. illuminate it and can create a font that is embedded (in svg) screen reader could read plain text, but if look at it...change to readable font by user preference. so, at core it is a letter. similar to embedded fonts in css. can apply to just the first letter. it's still overwritable. this is an issue for pdf. fonts are drawings of characters. in pdf, critical to know what character a glyph represents. 2. Are we trying to address issue of background obscuring what is there or how readable the default font is? 3. Do these need to be covered separately or in the same guideline? Do we need to cover both of them? Have we already covered the issue in the "map to unicode" guideline? if not readable, still map back to unicode. No, that is for instances where it can not currenlty be mapped to unocide, but these characters (although heavily illuminated) would be mappable. partly, user agent issue. perhaps draw attn to fact that depend on ua guidelines. once represented in unicode and assuming it is valid, then css could handle it. action: editors add an example to the unicode guideline, about hard to read font, due to UAAG the UA could swap font. Another interpretation of the current wording ("provide a mechanism") is that an author would have to write a script to increase the contrast if it isn't enough. A UA-independant solutions might involve other inaccessible techniques such as client side scripts. This statement cause a discussion about the "content must work when technologies not supported" checkpoint. what are the base technologies? if an author uses an inaccessible technology, but the user should be able to control contrast, then the author can conform to this guideline (i.e., if a mechanism is provided, one could conform to this checkpoint) but if it is not accessible, then fail that part of the guidelines. Do we want to make sure that users can manipulate a browser to increase contrast or that authors must provide mechanisms? Since we opened up the discussion, we went back to the original intent of the guideline: foreground content is distinguishable from background...for visual default presentation. It was suggested that we change this back to "make foreground content easily differentiable from background." But, this doesn't seem to clarify the issue. Other issues: 1. make it possible use ua to distinguish foreground/background. 2. originally, w/out asst. tech and w/out ua it is easy to tell the difference (started at level 2). today, talking about ua and non-ua. 3. guideline said default but sc said "mechanism" 4. if you have a formula to determine contrast, difficult to say if enough contrast or not. how many pixels does it take for something to not be readable? don't think we can find a formula. This has been a good discussion, but there are several issues to discuss. To move forward, a group of folks will work on a proposal to discuss. action: wendy, loretta, mat, gregg, doyle work on color contrast guideline(s) Topic 2: Guideline 1.7 In default auditory presentations, make it easy to distinguish foreground speech and sounds from background sounds. http://www.w3.org/WAI/GL/2003/11/18-f2f-review-draft.html#audio-contrast History: this guideline and the previous used to be one guideline that was generalized to talk about contrast. It was separated because some believe it easier to think about the different levels of success criteria if keep audio and visual separate. There is concern that by separating them we have a guideline (1.7) that only has level 3 criteria. Questions about the success criterion: 1. Is 20 dB of difference between loudest background noise and softest foreground noise or at any given time? proposal: "does not have background sounds that are at least 20 dB...x% of the time" thus, could be a cymbal crash (that would conflict with part of foreground) but could still be ok. 2. most auditory content is a single track, thus no way to control foreground vs background noise. Thus, if you want to go beyond level 1, you have to save this as multiple tracks? Or, does an author not have level 2 if have content that has lots of noise? 3. what about a text transcript as alternative? was this a level 3 at one time? what if audio is always captioned? discussion about moving this to level 3, since if have a movie or other audio content, make it impossible to conform to level 2? if there is a transcript or captions and you have difficulty understanding what is said, why is that not accessible? thus, it is nice to do this one (thus level 3), if have captions or transcript then accessible. it's only the fact that there are captions, that make it possible to move this to level 3. for wording: audio content does not contain audio sounds or are at least 20 dB... except for occasional sound bursts...short sounds. have to clarify "short" "background" and "short" background and foreground may switch, depending on content. e.g., person entering parliament. when person talking, trumpets are background. when trumpets move to foreground, get turned up. resolved: use the plain lang rewrite. make it a level 3. explain why it is 3 and not 2. -- wendy a chisholm world wide web consortium web accessibility initiative http://www.w3.org/WAI/ /--
Received on Monday, 8 December 2003 13:31:03 UTC