Any time you use an image, graphic or non-text content in a project add alternative text (e.g. alt text). People who experience blindness or have visual impairments may not clearly see an image on a screen adding meaningful alt text is important Images should have a specific purpose when used, and an alt text supplies the function of the image or briefly presents the purpose of the image's link target. Though there is no limit restricting the length of an alt tag, it may help to think of an alt tag as a Tweet (140 characters or less).
Information images are images not used as a like. They are present to convey meaning or information. The alternative text foir information images should describe the image and its purpose for supporting the page content.
Action images are images that have an action, such as a linked image. The alternative text for an action image should provide context for the target of the link.
Larger data images, my not be images but other forms of non-text content such as charts and graphs. The information present in the graph or chart needs to have a text equivalent.If information is too large for an alt tag, included the data table for the chart or graph.
Avoid if possible. Text embedded into image files are not accessible to some assistive technologies. Instead it is best to use HTML for text. If you must use an image of text, then use the text in the image as the alt tag, do not identify the specific image scene or elements. The text is typically the important information in a text image.
Decorative images do not have a significant function except for decoration. These images can have a blank or null alt text (alt=""). Please note, the OU campus editor requires all images to have an image description before they can be uploaded. In these cases, it is best to add the image description anyway.
Images can have different meanings and intended information. Be clear with why the image is present and what information the image conveys. Below are a few scenerios that you may encounter when writing alternative text for images.
Avoid blinking content. Flashing or blinking content (particularly content in red) can cause seizures in people with photosensitive epilepsy as well as other photosensitive seizure disorders. Limit use to only when necessary. If blinking conent is necessary content should not flash more than three times in one second.
Images Retrieved from: https://pixabay.com/en/cardinal-bird-perched-male-nature-529695/
Provide meaning and/or functon of the image in the context of your message.