- From: Michael Vorburger <mike@vorburger.ch>
- Date: Wed, 4 Nov 1998 01:17:37 +0100
- To: <w3c-wai-er-ig@w3.org>
Hello everboy First of all, sorry for having been quiet during some days, but restart at university brought a lot new things to look at and chose from. Among them, I finally chose a WAI related semester project. After consulting with my supervisor, we agreed that an ALTifier would be more appropriate for the time frame given for such a semester project, than the text-equiv filter that I also suggested. Briefly, this ALTifier will insert ALT attributes into IMG and other HTML tags. In "user mode", the ALT text will be "guessed" by various heuristics, such as context, following the link if the image is one, and maybe OCR. Three front-ends will be built around the same core engine: a) A proxy server in "user mode" setting ALT without human intervention, b) some UNIX command-line tools in "author mode") to set/retrieve ALT for an entire site, then edit them manually where appropriate and c) an interactive site-wide Windows GUI, this is also in "author-mode". Both "author-mode" modules (Win GUI and UNIX CLI) have a "Suggest" function which will invoke the guess-function used in "user mode" for the proxy server. Authors will be encouraged not to simply launch the tool using "Suggest" for all ALTs, but interactively edit them. Find below an early draft of the spec of this project. It's unfinished, but I wanted you to know about for tomorrow's phone conference. Regards, Michael _______________________________ 1.1 Three Front Ends and One Back End The back-end core engine will provide a very simple C or C++ calling interface. Three front-ends will be built around the same core engine: · A proxy server setting ALT without human intervention. This is called "user mode". · UNIX command-line tools to set/retrieve ALT for an entire site, then edit them manually · interactive site-wide Windows GUI. This and the above tool are running in called "author-mode". Both "author-mode" modules (Win GUI and UNIX CLI) have a "Suggest" function which will invoke the guess-function used in "user mode" for the proxy server. Authors will be encouraged not to simply launch the tool using "Suggest" for all ALTs, but interactively edit them. This tool can currently not be used as a browser plug-in. Further front-ends for the easily interchangeable system could consists of a CGI interface, an ISAPI filter (M$) or any other such technology. Other offline post-processes in "author-mode" that crawl a local site and do some editing can be thought of as well. 1.2 Image classes Illustration Dots, Bars (horizontal rulers) Icons/Symbole (Textergänzung oder Textersatz) Cliparts (Illustrationen) Thumbnails (Vorschau-Grafiken) <a href="bigpict.jpg"><img src="minipict.gif"></a> 1.3 How To "Guess" an ALT (Used Heuristics) These there the "heuristics" used to guess an IMG's or other tag's ALT text, in order of priority: ¨ return an empty ALT="" is the IMG seems to decorative only. This is the case if the image is very small, like 1x1 or 3x3, or if it is not a pure IMG link, meaning there is some text between IMG and /A, or ... etc. etc. ... ¨ If in authoring mode, and the image is inside a pure1 A- IMG-/A link, and the link target is an HTML document use the "document's short title" as defined below. The "authoring mode only" decision has been made having waste of bandwidth (fetching all linked pages) in mind. This might become a configurable option. ¨ OCR, with an Interface to "Xerox Textbridge" (???) if installed. (This feature is not of first priority.) ¨ If the tag has any of the following attributes, chose them as ALT, in order of priority: NAME, ID, LONGDESC, ... (did I forget any HTML4 stuff?) ¨ the filename, cutting off the path and extension of the file. This is based on the hope that the webmaster or graphics designer gave a meaningful names to their images, like help.gif or options.gif etc. ¨ querying some ALT text server, yet to be set up, as outlined in http://www.w3.org/WAI/altserv.htm (This is not a first priority.) This tool could request ALT text from and submit new descriptions to the server. content of the image by. Read / do ... Lang/nouns... 1.4 Tags to ALTify ALT and/or TITLE and/or ... ??? ¨ IMG: ¨ IMG inside A/HREF Link, often Buttons, <a href="datei.html"><img src="button.gif" border=0></a> ¨ body background: ¨ CSS Support ?! (necc to follow and parse .css ?) ¨ OBJECT / APPLET ? ¨ Image MAPs, Client side only. (A server side image map could be treated by simulated clicks on a raster of every eg. 5x5 pixels. This approach is not followed in this project though, partially we defined not to follow links in user mode, but only in author mode.) ¨ <embed (Netscape specific multimedia) ¨ <img dynsrc="hochzeit.avi" (IE specific multimedia) ¨ <FRAME SRC=url TITLE=alt> Notice that frame uses TITLE instead ALT attribute. ¨ <INPUT SRC=url ALT=alt> 1.5 Platform & Environment The original version was developed under MS Windows using Visual C++ 5.0, as this system was available and the author had prior usage experience. Most of the code is platform neutral, and a port to UNIX (gcc) should be possible in a reasonable amount of time. The HTML++ library uses RTTI, but most C++ compilers should provide this formerly advanced C++ feature by now. 1.6 Modules & Components The ALTifier is built of the following modules and components: ¨ ALTifier back end, written in platform neutral C++ compiled by Visual C++ and gcc ¨ Win GUI front end, written with C++ Builder RAD tool by Borland/Inprise ¨ UNIX CLI front end, written in C with gcc ¨ HTTP Proxy front end, inspired by GNU wwwoffle ¨ Crawl engine for interactive Win & UNIX front-ends, shared code with KISSfp2 ¨ OCR interface to ... TextBridge ... ??? (Win DLL?) ¨ Natural language recognition engine ??? ¨ GIF toolkit to determine width and height, maybe get and set GIF comment, inspired by gd3 _______________________________ 1 A "pure A-IMG" link is in this document defined as one where /A directly follows IMG, with no descriptive text following the image. 2 http://www.vorburger.ch/kissfp 3 http://www.boutell.com/gd (?) ---- Michael Vorburger <mike@vorburger.ch> & <michael.vorburger@epfl.ch> GO DIGITAL: No more oil-based toner on flattened dead trees! HOMEPAGE: http://www.vorburger.ch
Received on Tuesday, 3 November 1998 19:17:25 UTC