- From: Jukka K. Korpela <jkorpela@cs.tut.fi>
- Date: Wed, 12 Mar 2003 00:41:33 +0200 (EET)
- To: w3c-wai-ig@w3.org
On Tue, 11 Mar 2003, Bill LaPlant wrote: > It seems to me that in providing text descriptions of graphics, we really must > consider the intent of the content provider in deciding the thoroughness of the > descriptions. I guess so, but this is not what alt attributes are about. An alt attribute is meant to be a replacement for an image, not a description of it. Unfortunately even the W3C recommendations are partly confused in this issue. One of the causes of this confusion is probably the fact that in quite a many cases, it is not _possible_ to write a replacement for an image into an alt attribute, either due to the technical limitations of the attribute structure and implementation or due to lack of time and other resources, or perhaps due to the inherent nature of the image. I've written a partial explanation of the "great confusion" (alternative versus description): http://www.cs.tut.fi/~jkorpela/html/alt.html#idea If you use a picture of Mona Lisa merely as decoration, alt="" is adequate. If you use it on a page about Leonardo da Vinci, then maybe alt="Leonardo da Vinci painted Mona Lisa." (or something in a little more stylish language) would be adequate, if that's what you are trying to say. If the page is _about_ Mona Lisa and the picture is included so that the user can look at it while reading the commentary, then obviously there is no way to write a replacement. What we would really need is a coded way of saying that the image contains essential visual information that cannot be expressed in words and a name, or label, for the image so that it might be associated with something that the user knows otherwise. I have suggested the use of notations like alt="[Mona Lisa]", in lack of anything better. The brackets would tell that it's not a replacement but a name, or description. > If the image is provided to "dress up" the page, not, therefore > adding to the substance of the content, then it would seem to me that the briefer > description would be appropriate for the alt tag. For what purpose? Why would you tell me that a page contains red bullets just because you've decided to use red bullets as separators or bullet points? Wouldn't it then be equally important to tell me, for each and every list item on the page, that a style sheet has been used to make the list bullets red (assuming, for the sake of argument, that CSS would let me do that, as it should)? > If, on the otherhand, the image > is illustrative of some key point to be made that amplifies the rest of the content, > then a more detailed description would be appropriate. No, a textual equivalent should be given. It should be the text that you would write if no images existed. > If the designers are > enamored of a detailed description of the image used for decorative purposes for > some reason, in addition to the shorter alt tag, they can always add a "D" link > which can be by-passed by the reader in a hurry. No, that would just add annoyance to foolishness. The "D" link concept has largely been abandoned even in theory, and it was not much used in practice, but no matter what you use as a link, there should be something potentially useful at the other side of the link. If an author thinks that explaining the decorations is somehow relevant, then such things would belong to the footnote-like stuff at the end of the page, an "about this page" section. And if there's a link to a document about some decoration, then it should be clearly identified as such in the link text. -- Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Tuesday, 11 March 2003 17:41:36 UTC