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Alternative Text

Paligo recommends that you add alternative texts to your media files. Aim to provide a text description as if you were explaining it to someone with a visual impairment. This text becomes visible when the media cannot be shown due to a slow connection or if a screen reader is used.

Alternative text (alt text) is used as a fallback for an image if the image cannot be displayed, or for improved accessibility for both videos and images. By using alt texts you improve search engine optimization (SEO) and the accessibility for people with certain disabilities. The alternative text can be read out by some screen readers. To use alt text in PDF output, see Activate Alternative Text for PDF.

Alt texts can be added in two ways for images, either:

  • Add an Image Description - It will be shown everywhere the image is used. The description is always in the default language and cannot be translated.

  • Add the Alt Element - It will override the image description for a specific topic. The alt element can be translated.

Image_Description_small.jpg

If an image does not have a description or an alt element, the image title is used instead. By default, the title property is set to the image file name.

Tip

You can use the Image Title Attribute setting to add a title to an image in your HTML5 output, see Hover Text using the Image Title.

Add an Image Description

Enter a description that will be shown everywhere the image is used and will serve as an alt text. The image description is always in the default language and is not translated.

Aim to provide a text description as if you were explaining it to someone with a visual impairment. Try to include a keyword or synonym for your page. Do not use images for "keyword stuffing".

Note

If an image does not have a description or an alt el, the image title is used instead. By default, the title property is set to the image file name

To add a description that will serve as the image alt text:

  1. Add the image to the topic.

  2. Right-click the image and select Edit properties. Comment_small.png

    Alternatively, find the image in the Media section of the Content Manager, select its dotted menu ( ... ) and choose Edit Image.

    Image details dialog. It provides details about where the image is used, its filename, its taxonomy tags, and its dimensions. There are also settings for setting language variants and an alt text description.

    Paligo displays the Image details.

  3. Enter a Description that will serve as the image alternative text. It will be used wherever that image appears. However, if the image has an alt element in a topic, that will override the description. If it is a figure, the textual content of the figure title element will override the description as well if no alt element content is present.

  4. Select Update description to save the text.

Add the Alt Element

You can use the alt element for both images and videos. The alt element can be translated and it only applies where you have added it. This approach is useful when you reuse an image or video in many topics, but you want the description to be different, depending on the context of the topic. If you want to switch image for different languages, add the alt element to override the image description for affected topics.

Aim to provide a text description as if you were explaining it to someone with a visual impairment. Try to include a keyword or synonym for your page. Do not use images for "keyword stuffing".

Note

If an image does not have a description or an alt element, the image title is used instead. By default, the title property is set to the image file name.

  1. Add the image or video to the topic and then select it.

  2. Select the mediaobject element in the Element Structure Menu and choose Go to element.

    Paligo editor showing that the mediaobject element is selected in the element structure menu. This reveals a dropdown menu. A callout arrow points to the Go to element option on the dropdown menu.

  3. Press Alt + Enter ⏎ (Windows) or Command ⌘ + Enter ⏎ (Mac) to display the Element Context Menu.

  4. Enter alt and select it from the menu.

    ALT_Option_small.jpg

    Paligo adds an alt element above the image or video (but inside the mediaobject element).

    An image in a topic. Above the image, there is an alt tag, which shows the word "alt" by default. A callout arrow is pointing at the alt tag.

  5. Enter the description in the alt element.

    alt-text-rover-on-surface-of-mars.jpg

  6. Select Save. Save icon.

Activate Alternative Text for PDF

Your images in PDF outputs can use alternative text that appear as a "hover pop-up" when you position the cursor over an image. For accessibility, the alt text can also be detected by the "Read Out Loud" feature in Adobe Reader.

pdf-alt-text.jpg

To use alt text in PDF output:

  1. Add the alt text to the images, see Add an Image Description or Add the Alt Element

  2. Select Layout in the top menu.

    Paligo editor. The Layout option in the header menu is highlighted.

    Paligo displays a list of Layouts. The list is empty if there are no custom Layouts in your Paligo instance.

  3. Select the Layout you want to update or Create a Layout.

    Tip

    You can copy the URL of the Layout Editor and paste it into a new tab in your browser. This can be useful if you frequently switch between your Paligo content and the Layout settings.

  4. Select General > Misc in the sidebar.

  5. Set Generate tagged PDF to Enabled.

    generate-tagged-pdf-enabled.jpg

  6. Select Save.

When you publish using this layout, the PDF will be tagged and will include the alt text you have set for your images.

Important

To be able to use alt text in PDF output, it is important to know that:

  • The PDF processor cannot complete the publishing if your content contains tagged PDFs embedded as images when Generate tagged PDF is enabled. This will result in a "production failed" error. You have to use untagged PDFs as images or use different types of image files.

  • The layout must have Generate tagged PDF enabled.