Handling Images and Non-Text Content (MS PowerPoint)
People who have visual impairments need alternative ways to access the information conveyed by images and other non-text objects (e.g., charts). This is accomplished by assigning alternative text to these elements in the document. The alternative text is then read by screen readers to tell the end user what information is being conveyed with the graphical elements on the page.
In some cases, graphical objects are simply decorative and not used to convey information. Alternative text is not needed in these instances and the objects are marked as “artifacts” in the PDF. While there is no support for marking graphics as artifacts in MS PowerPoint, CommonLook Office GlobalAccess does make this possible.
The Purpose of this checkpoint is to ensure that all non-textual objects are either assigned a meaningful alternative text describing the information conveyed graphically, or that these objects are artifacted in the PDF.
- Near the bottom of the CommonLook Office GlobalAccess panel, check the “Show all” radio button. This provides a list of all graphical elements used in the document.
- Verify the textual description, if any, describes the purpose of the selected non-text object. If it does not, enter an appropriate description.
- If the object is a picture of text, enter that text in the “Actual Text” box as opposed to the “Textual Description” box.
- If the object is a mathematical formula then check the “Image is a Formula” checkbox and use the “Textual Description” box to write the alternative text for the formula.
- If the object is not used to convey information (e.g. decorative shapes), then simply check “No textual description required image used solely for presentation.” Note: According to Health and Human Services (HHS) guidelines, all watermarks and background images should be removed from the document.
- Click the right facing arrow next to “Task” to move to the next object in the list.
- Repeat until all the listed objects have been assigned a meaningful text description or have been identified as images used solely for presentation.
Note: Images that are used solely for presentation will be marked as “artifacts” and will not be identified or read by assistive technology.
The screen shot below illustrates the steps to adding Alternative text and/or artifacting images as outlined above:
Multiple shapes are often used together to create a single complex object (e.g., a flow chart). Before providing a textual description, group the shapes together. Grouping multiple shapes allows the author to provide one alternative text for the concept being conveyed by a set of images. Otherwise, shapes that are not grouped together would all require their own individual alternative text.
In CommonLook Office Global Access, in the “Objects” panel, select the items that should be grouped together and use the buttons below that panel to group them.
Flattening Multi-layered Objects:
Similar to grouping multiple objects that are used to convey a single concept, sometimes graphics are created using multiple layers. When this is the case, these layers should be flattened so that the image can be given one alternative text description.
The proper tagging of mathematical formulae is addressed in the “Instructions” section above in step 2.2.
Other HHS Considerations:
The U.S. Department of Health and Human Services has the following considerations to also keep in mind when authoring MS Word documents to their standards:
- The document should be free of scanned images of text.
- Scanned signatures must be removed from the document.
- Complex images such as graphs or charts should have a caption or some other descriptive text near the image itself.
- Images (as well as text) should appear “Crisp and legible.”
Choose the “Show images with no textual description” radio button to bypass objects that already have alternate text. Important: Choose this option only if the accuracy of the alternative text has already been confirmed.
Some organizations have policies that govern the “quality” of the textual descriptions for images to ensure that the alternative text is accurate to the content shown by the images. CommonLook Office GlobalAccess facilitates such policies by providing a warning when an image description may not be of sufficient quality, for example, if the description is a filename, or contains fewer than three words. Advanced users can manage the alternative text quality control settings using the Checkpoint Preference tab.
This checkpoint is relevant to the following regulations, guidelines and standards:
|Section 508 – 2001 Regulations (USA)||2001||“Web-Based Information & Applications”||(a)|
|W3C WCAG 2.0||2008||Web Content||SC 1.1.1|
|Health and Human Services – HHS (USA)||2013||PDF File 508 Checklist||ID 2.1|
ID 4.1 – 4.5
|ISO 14289 (PDF/UA)||2012||PDF Technology||Section 7.3|