Alt text for authors

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Images are an important way of communicating data in a user-friendly format. But did you know that unless an image also has a textual description, it is not accessible to all readers.
Alternative text or alt text, is a textual image description. It communicates the important visual information and function of the image to people who use assistive technology, such as read aloud screen readers.
It also enhances content discoverability because alt text is indexed by search engines. With the help of AltText, everyone can equitably access and understand visual content.
The length of alt text can be short or long depending on the complexity of the image. For example, there are simple images that can be described in under 200 characters.
These only need a short alt text, approximately 20 to 30 words. Complex images such as anatomical illustrations or populous flow charts cannot be described meaningfully with short text.
For these images, the alt text is accompanied by a long description which gives an extended, detailed equivalent to the image.
Now, many figures have captions which are also written texts associated with the image. However, there are key distinctions between alt texts and figure captions, and they can't be used to replace each other.
Here's an example of an image and its figure caption. Figure 5.3.
Example of an LCA for incineration, pyrolysis, and gasification. A figure caption is visible text that puts the image in the context of the rest of the text.
It may briefly describe the image and or its purpose, but its role is not to give a visually rich description. On the flip side, alt text provides a concise literal description of the image conveying all elements that are important to understand its intent and meaning.
So the alt text for this image would describe the structure of the main three sections, key inputs and outputs, and the pathways shown.
The alt text does not repeat information from the caption. It works together with it to provide a complete description.
Elsevier includes alt text for all images that convey information in newly published content. It is a legal requirement to comply with accessibility legislation such as the Americans with Disabilities Act or ADA and European Accessibility Act or EAA.
Elsevier cannot publish content without it. Alt Text is produced by Elsevier.
And then added to proofing tools for authors to review. And either accept or suggest changes where needed.
While reviewing the alt text, keep in mind that it is there to provide an equivalent description of what the image shows, unlike the figure caption.
It can be helpful to imagine that you are describing the image in detail to somebody over the phone, explaining the important visual information you want to convey.
Please check that the visual content, technical terminology, and key details have been represented accurately and completely.
To show this in practice, let's take this illustration of a heart defect from a nursing textbook. The original intention of the image is to highlight the deformity of the heart and how it changes blood flow, so the alt text is organized around fully describing that.
The anatomy of the human heart, focusing on an atrial septal defect or ASD. The heart is depicted in a cross-sectional view representing its four chambers the right atrium, left atrium, right ventricle, and left ventricle.
The atrial septal defect is highlighted as a hole in the wall or septum separating the left and right atria. Arrows indicate the abnormal flow of blood from the left atrium to the right atrium through the defect.
The image also represents the major blood vessels connected to the heart, including the superior vena cava, inferior vena cava, and pulmonary veins.
The illustration emphasizes the physiological impact of the defect, which can lead to increased blood flow to the lungs and strain on the right side of the heart.
You can find even more information about alt text in the author guidelines and the alt text guide in the proofing tool.