Automatically finding inaccessible alternative texts in web pages

September 24, 2010

A publication on Automatic Checking of Alternative Texts on Web Pages (Olsen, Snaprud, Nietzio) was recently published.

Often alternate texts for images, maps of audio files, are generated by web publishing software or not properly provided by the editors. For humans it is relatively straightforward to see which alternative texts have been generated automatically as the texts are in no way describing the corresponding image. Examples include texts such as ”Image1”, texts which resemble filenames such as ”image12.png” or ”insert alternative text here”.

The proper method for adding images to a document is when an editor uploads an image for article and can / must provide an alternative text in the CMS.

There are however several improper methods which results in in-accessible automatically generated alternative texts:

  • The editor uploads an image and uses the default alternative text.
  • The editor uploads an image for an article and the CMS generates some (often strange) alternative text.
  • The editor uploads an image but have no possibility to write an alternative text.

Following are some example of automatically generated alternative texts (Image source wikipedia)

A picture of a dog eating with a correct alternative text: Golden Retriever Eating

Correct Alternative text "Image12.png" HTML: <img alt=”Golden Retriever Eating” ... />

A picture of a dog eating with a wrong alternative text: image12.png

Wrong Alternative text "Image12.png" HTML: <img alt=”image12.png” ... />

A picture of a dog eating with a wrong alternative text: image12.png

Wrong Alternative text "Image12.png" HTML: <img alt=”image12.png” ... />

For people who cannot see non-textual content alternative texts are crucial to understand and use the content and automatically generated alternative texts may impose web accessibility barriers. Most automatic accessibility checkers only detects for the existence of alternative texts. The above mentioned texts, which are not describing the corresponding image well and are thus not considered accessible, will not be detected.

The paper introduces a pattern recognition approach for automatic detection of alternative texts that may impose a barrier. The introduced algorithms reach an accuracy of more then 90%, which should hopefully be a step towards improving the usefulness of automatic accessibility checking. Additionally, it could be useful input of manual accessibility checking.

(Full disclosure: I’m a co-author of the paper)


A collaborative approach for improving local government web sites

July 30, 2010

A publication on how to facilitate collaboration between local government and vendors entitled Accessibility of eGovernment web sites: Towards a collaborative retrofitting approach (Nietzio, Olsen, Eibegger, Snaprud) has recently been published.

Changing a local government web site is often a long process which normally includes vendors, editors and specialists in local regulations and legal enforcements. Results from benchmarking studies are often a good facilitators, but the results alone are of limited use when it comes to updates in practice. This is especially true if the web site updates are relatively small such as removing accessibility barriers. Thus, the paper presents an approach for rapid accessibility updates of government web sites. The approach uses benchmarking results together with forums and online checkers.

Collaborative process between municipalities, vendors and eGovMon. Vendors and municipalities collaborate through the eGovMon forum and through physical discussions. eGovMon organizes workshops and seminars for vendors and municipalities respectively.

Collaboration process between municipalities, vendors and eGovMon

The approach, visualised in the figure above, is applied to a group of Norwegian municipalities who want to improve the accessibility of their web site.

Accessibility benchmarking often fail to have an impact. This may be because of the following reasons:

  • The results are not detailed enough to be used for implementation purposes.
  • It is not clear what part of the publication chain the problem is located (in the CMS or introduced by the editor).
  • The maintainers do not have the technical knowledge to fix the problem.
  • The barriers are fixed in a one-off effort. However, since there are no quality process in place to detect if newly added content is in-accessible.
  • The benchmarking is carried out as a one-off study so that progress cannot be evaluated.

The presented approach includes three areas:

  1. Regular Benchmarking reports: Bi-monthly benchmarking reports of all municipality web sites. In these reports the editors of the local web sites can see how any web site updates affects accessibility.
  2. Online accessibility checkers: An interactive environment where editors and developers can instantly check their web pages and web sites. This allows for developers to incrementally remove accessibility barriers. (Blog post on Web Accessibility Checking)
  3. Online forum: Often times, it is clear where in the production chain an accessibility barrier is located. For example, when the logo of a web site is missing an alternative text, this is likely to be a problem caused by the CMS. However, if an individual image in a document is missing an alternative text, it could be because the editor did not provide this. Such discrepancies could lead to the situation where editors blame the CMS for accessibility problems, while the vendors claim that the editors are not using the CMS correctly. In the forum, editors can ask how to fix a specific barrier for a given CMS should be fixed, and the vendors can reply.

This approach allows for local web site editors to use e-government benchmarking results together with an online forum to fix any accessibility issues with the web site. Furthermore, the editors gets knowledge of which issues they cannot fix themselves, but has to be carried out by updates of the CMS software or web site template. Even though this collaborative concept was applied to web accessibility barriers, it may be useful for other areas of local e-government as well.

(Full disclosure: I’m a co-author of the paper)