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Accessibility on the web has been an issue for over a decade, and it remains a crucial--but often overlooked--element of web design. Instructor Zoe Gillenwater explains the concept of accessibility as it applies to the web, and describes how it affects the audience. She also covers how to set up accessibility testing, and how to apply accessibility principles to new and existing sites using standards-compliant markup and CSS. Exercise files accompany the tutorials.
>> For those not yet familiar with web accessibility the first thing they think of is alt tags on images. There's actually no such thing as an alt tag but it's true that images must be provided with alternative text and that failure to do so is one of the biggest problems for screen reader users and other people or devices that don't use images on the web. Both the section 508 and WCAG guidelines specify that text equivalents should be provided for every non text element. The primary requirement that this is met is through the alt attribute on the image element but its not the only way as we'll talk about in this and later movies.
Also note that the standard is a text equivalent not a description of the image. The quality of the text you choose is just as important as whether it's there or not. We're going to look at a few different types of images and talk about high quality text that would be appropriate for there alt attributes. To practice adding alt text we are going to work on the file government.html. If you are following along with the exercise files, this page is located in the folder 0601 of the chapter six exercise files.
The first image on this page is the logo image. If we look down in the properties inspector and look inside the alt field you will see that it is blank, that means that it currently has no alt attributes set. We need to give it alternative text so that screen reader users and other who are not browsing images such as text browser users, people who are on very slow dial up connections or small screen devices such as cell phones and PDA's will be able to tell what the image is. We don't want to describe to image its not important to our users what the visual characteristics of the logo are.
We also don't want to say logo in the alt text. That again is the description and it's not important for our users to know that it's a logo, rather they need to know the information that the information conveys. The purpose for the is image is to identify the site as being about or by the town of Wardscott so click inside the alt field in the properties inspector and type town of Wardscott. In general an image of text ought to have the same text set for its alt attribute.
For example if you had graphic buttons being used for links you would use the alt attribute services on the services button. You wouldn't use the text services button or services image for the alternative text if you just use the same text that is shown on the face of the button. Alt test is especially important when the image has a link surrounding it. In these cases the alt text effectively becomes the link text and as we talked about earlier its very important for our link text to be clear and meaningful.
Scroll down the government page in Dreamweaver. There is a table at the bottom of the page with a number of DOC and PDF icons that are met to link to public meeting minutes documents. Each one of these images needs to have alt text explains what the user will get by clicking on the icon. So click on the first icon, go down to the properties inspector and click inside the alt field, type word doc town council 5/31/08 meeting minutes.
So here for the alt text we used a description of where the link points to, this is the general practice you should follow for any images that are being used for navigation. Now lets click on the first PDF icon then go down to the properties inspector and click in the alt field. Here we'll type PDF of town council 5/31/08 meeting minutes.
You would follow this process on through the page for each one of these icons. Again note that we haven't described what these images look like or put the word image, icon, graphic, anything of that nature inside of there alt text instead we've described what the purpose of the images. So follow these guidelines for creating text equivalents for your images whenever they convey information. Sometimes though images are not conveying information rather they are decorative, other times the image is conveying information but that information is given elsewhere on the page.
In these situations it can be harmful to accessibility to put text in the alt attribute. We'll talk about that next.
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