- From: Anne Pemberton <apembert@crosslink.net>
- Date: Tue, 31 Oct 2000 18:20:54 -0800
- To: Wendy A Chisholm <wendy@w3.org>, Web Content Accessibility Guidelines <w3c-wai-gl@w3.org>
Wendy and all, Thanks to the many of you who have helped enlighten me. In twix moments during the day, and during the assembly, I checked out most of what was recommended. Wendy, your definitions were the final clinching ... I tried to download the viewer at school, but kept getting a "unavailable page" message, but got it at home just a few minutes ago, and was finally able to see something exciting in svg ... the clock on the adobe page. I understand that the Flash, which I liked on that Lilly Frog page, may have been vector graphics, perhaps svg ... which then makes me wonder why Flash is still "inaccessible" if Flash graphics have all these assessibility possibilities ... For educational sites, I can see advantages of scalable graphics so that the output can be sized as needed ... blown up to full page size, perhaps larger, to print, full screen size, and if it can all be done from a thumbnail sized file on the web, it's great! It could be a boon on sites where you want the graphic to appear large on click ... The major drawback is the fact that it's said not to do photos well yet ... A plus is that graphics can be created into svg using at least two major graphics softwares, Corel Draw and Adobe. A distinct downside is that you're back to that nasty mess of saying the user has to download something in order to see what's on your site ... free and fast is good ... but it still takes planning before the first use ... and replacing everytime your system crashes and you have to re-load everything you can remember you had ... (needless to say that I am well acquainted with inadequate backup ... always two weeks out of date, and the only free download I save is Eudora, none of the rest ... ) Thanks for your help, folks. I am seeing advantages to svg and a reason to suggest it in the guidelines. But I think that the realities of the limitations need to be there too. Perhaps as a sub-number under Guideline 3 ... to define the graphics that can be done in vector graphics (at present, free of bugs!) ... and those that will need to be in bitmaps ... the techniques should tell what software needs to be used, and how to put the "download free software option" on the page ... It is a bit disturbing that a special download is needed ... that may add an "unnecessary" hardship on cognitively-disabled folks, who would benefit from the scalability of the graphic ... Anne At 04:24 PM 10/31/00 -0500, Wendy A Chisholm wrote: >Anne, > >"Raster graphics" is defined at: >http://whatis.techtarget.com/WhatIs_Definition_Page/0,4152,212871,00.html > >"Vector graphics" is defined at: >http://whatis.techtarget.com/WhatIs_Definition_Page/0,4152,213284,00.html > >Therefore, please reread the section of "Accessibility Features of SVG" >where it gives an example of a raster-based image versus a vector-graphic. >http://www.w3.org/TR/SVG-access/#What > >Note how the raster-based image (the PNG figure) of the tiger starts to >break up as it is enlarged while the SVG figure remains smooth. > >Because instructions on how to draw the image rather than pixel values are >sent to the browser, the browser can make the necessary changes when the >user wants to increase the size of the image. > >The boon for accessibility is that you can include text in SVG. Thus, if >you make a logo that has text in a funky font, the user can increase the >size of the image and it will remain readable. Also, since you are sending >instructions to the browser you are sending markup. Within those >instructions (markup) you can include lots of information about the >image. This gets really interesting when you have a diagram or a chart and >a bar in the chart means something (e.g., bar #1 = how many books were sold >at amazon.com this june vs bar #2 = how many books were sold in july). If >done well, I could navigate the image and grab this information as I go. > >Do you see the difference and the benefits to accessibility? >--wendy > >At 10:20 AM 10/31/00 , Anne Pemberton wrote: >>Jason, >> Checked out both sites, and couldn't find an example of what SVG >> does. >>Lots of verbage, but no "let me see" ... There is a comparison of a graphic >>in png and svg, which shows svg enlarged nicely next to a png that was too >>small to increase. But the alt tag for the enlarged graphic was "enlarged >>svg", and provided no further information on the graphic. What am I >>missing? Nothing I did on the small svg graphic caused it to enlarge. >> >> Further, although I've seen png somewhere in my graphics tools, it >>isn't a format I use. I use mostly jpg and sometimes bmp (reduced to jpg). >>Neither of these were mentioned. >> >> As best I could tell, the only difference between jpg and svg is that >>svg lets you do "something" with a description, but I couldn't see an >>example of what that "something" is. Is it there, and I didn't look long >>enough at the site? (I hate horribly long pages that have to include a >>table of contents!) >> >>Seems it's a long way to go to insure that graphics get alt tags, and a way >>fraught with better choices to do the same thing... >> >> Anne >> >>PS: I'm not a math or an art major and have no idea what the difference >>between vector graphics and raster graphics is ... couldn't get even a >>pinch of a clue by reading the information. >> >>At 11:19 AM 10/31/00 +1100, Jason White wrote: >> >SVG is a graphics format currently under development by W3C. See >> >http://www.w3.org/Graphics/SVG/ for further details, including the >> >excellent note entitled Acessibility Features of SVG: >> >http://www.w3.org/TR/SVG-access/ >> >>Anne L. Pemberton >>http://www.pen.k12.va.us/Pav/Academy1 >>http://www.erols.com/stevepem/Homeschooling >>apembert@crosslink.net >>Enabling Support Foundation >>http://www.enabling.org > >-- >wendy a chisholm >world wide web consortium >web accessibility initiative >madison, wi usa >tel: +1 608 663 6346 >/-- > Anne L. Pemberton http://www.pen.k12.va.us/Pav/Academy1 http://www.erols.com/stevepem/Homeschooling apembert@crosslink.net Enabling Support Foundation http://www.enabling.org
Received on Tuesday, 31 October 2000 18:57:10 UTC