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© Novática Information Technologies for Visually Impaired People Figure 4: Web Page Processed by ACTAW. they do not follow the grammar rules. Given the huge number of improperly designed Web pages there are, this makes the analyser a highly versatile tool. To improve the resulting code, situations that, while not incorrect, are not recommended are replaced. This is done by unifying criteria to specify colours, converting all definitions to a hexadecimal format instead of using a decimal format or the name of the colour. A large number of special characters are replaced by their equivalent HTML character so that they can be seen correctly using any browser. An example is the carácter 'ñ' which would be replaced by the identifier "&ntilde". The analysis of cascading styles is similar to that of HTML. A CSS document is analysed without any defined element other than the basic style definition structure. All the information is stored separately; i.e. multiple definitions are broken down into simple definitions. By applying the WAI standard we can modify, in a totally independent manner, the various elements that initially were the same, and so adapt the solution to each specific case. 3. Application of WAI Standards: Proposed Solutions We have analysed the various possible situations and how they match up against the guidelines proposed by WCAG, and we have applied the WCAG recommendations. It should be noted that the WAI standard is intended for website developers who know the semantic meaning of the content of a given HTML document; that is to say, people who are able to provide information not described by HTML tags, such as the meaning of an image. This makes the application of standards a truly arduous and complicated task. Some of the guidelines cannot be implemented a posteriori without knowledge of the Web page’s content of the page and its meaning. To obtain this information we need to perform a semantic analysis of the content of the page, which is a time-consuming process. Work is currently underway on possible solutions to this problem which may, in the future, deliver improvements to the application and Web accessibility in general. We go on to comment on a number of solutions proposed by some of the guidelines. To comment on all existing proposals and guidelines would be an overly lengthy and tedious task, so we have limited are comments to the guidelines we think will be of the most interest to our readers. Guideline 1: Provide equivalent alternatives to auditory and visual content Elements affected by this guideline are images, image maps, and embedded objects. Alternative texts are provided for these elements with all the information that can be ob- Figure 5: Improvement of Grammatical and Accessibility Errors using ACTAW. UPGRADE Vol. VIII, No. 2, April 2007 75
Information Technologies for Visually Impaired People tained from the HTML code. These alternative texts contain indications that tell us if they are used as links, if the reference does not exist, and what type of element we are dealing with. This enables us to differentiate an image used as a link from one that has no additional function. Alternative texts are also described for frame-based Web pages. These texts tell us the number of rows and columns and their position. Information is also included for browsers that do not support frames. Guideline 2: Don’t rely on colour alone Colours defined in the style sheets of the Web page are checked. If the colours do not meet the W3C colour contrast threshold, a new CSS document will be created with colours that contrast properly. The algorithm applied tries to ensure the greatest possible similarity between the original document original and the standardized one, since combinations of colours can provide information. The result of the CSS will not contain all the possible information, but it will allow it to be accessed. Guideline 3: Use markup and style sheets, and do so properly For this guideline the tags that markup visual effects are replaced by equivalent tags that markup emphasis for example. Contextual clues are added to be able to follow a list properly, regardless of whether it is nested. The application cannot detect text included in images, which means that any such text will not be available to voice browsers. Also, the coherence of headings and the proper use of tags that identify them depends on how well the creator of the document did his or her job, since it is impossible to know whether the start of a section is actually being indicated, or whether that section is more or less important than the one preceding it. Guideline 4: Clarify natural language usage Since the only source of information we have is the HTML code, the language used is identified and indicated by looking in the metadata. We are currently working on an agile and fast language detection system. In the event of any doubt, this system will also be able to determine the language with the help of other data, such as the topic of the website. Guideline 5: Create tables that transform gracefully All possible information contained in tables is provided, such as their size in the window or the number of rows and columns. Columns are grouped together according to their headings, if they have any. However, since we cannot obtain information about the content of tables, no specific measures are taken to ensure the proper alignment of tables, which may confuse users. We are currently looking for an effective algorithm to address this problem and so be in a position to offer users a fully user-oriented system. Guideline 6: Ensure that pages featuring new technologies transform gracefully For device dependent actions, keyboard and mouse equivalents are provided. However, no type of solution can be offered for elements created using JavaScript, since there is no analyser available for this type of code and so we are unable to modify it properly. We have already commented on the situation regarding frame-based pages, but there is one situation which is highly inaccessible; when one of the frames is an image. In this situation the image will be replaced by an HTML document which will contain the image together with all the information it is possible to include. This allows the user to obtain information about the image that would otherwise have been inaccessible. Guideline 7: Ensure user-control of time-sensitive content changes Animated images and embedded elements cannot be halted without losing information. Therefore special care needs to be taken when creating this type of content so as not to violate the standard. The application does however replace moving or blinking text if it was created using HTML. This change is performed using equivalent CSS and HTML techniques but may be disabled by the user from the browser. Any automatic refreshes and redirects in the page are also eliminated, thereby preventing end users from losing control over the pages they visit and over the content of those pages. Guideline 10: Use interim solutions This guideline deals with situations such as opening a new window with a link. Users may be confused when a new window appears without prior warning. The elimination of links that display information in new windows could lead to a loss of information, for example if a user wishes to return to the information contained in the previous Web page and that page depended on a user session. In view of this situation, we decided not to eliminate such links but rather to inform users when a link will open up in a new window. In this way users will have prior warning that a new window is to open and will be able to treat it like any other window and navigate around it properly. Figure 6: Analysis of the Improvement by Priorities. 76 UPGRADE Vol. VIII, No. 2, April 2007 © Novática
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