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Images: Alt-text and Image Descriptions

Reading systems and screenreaders can usually convert text to speech, but they cannot convert images to text. We use alt text ("alternative text") to replace the image for screenreaders.

A screenreader will stop on the image and read the Alt-text that you have written. This Alt-text is not visual, but is embedded in the code of the ebook. Part of your job is to write these descriptions. The content of the Alt-text depends on the type/purpose of the image.

The following is a video demo of how a screenreader reads an image description:

The term image description is an umbrella term referring to the concept of offering descriptions of images in text form. An image description conveys the same or equivalent information that a sighted reader would get when they look at a picture to someone with a print disability such as those who are blind or visually impaired. Image descriptions can be included in digital content in two forms:

  • Alt-text for simple and medium complexity images
  • Alt-text and long description for complex images

Remember, you are replacing visual information with text, not just describing an image. It is very important you follow these guidelines so your descriptions are clear to the reader and do not cause any confusion or cognitive issues.

There are no hard rules on how long Alt-text should be, but they usually around 2-6 sentences long. This is to help avoid cognitive overload. Cognitive overload can also happen if the description is not direct or concise. The description should walk the reader through the image and be very clear and direct. This can be a bit of an artform, so don’t stress out if you feel overwhelmed. This documentation is designed to help you learn how to write Alt-text and Long Descriptions.

Alt-text is done a bit differently for Children's Picture Books and Comics. Please visit their respective pages Alt-text for Picture Books and Comic Book/Graphic Novel Description: Introduction for more information.
Every image must have a description unless it is solely decorative. If you come across words that are images please refer to the section "Working with Images of Words and Different Alphabets" on the Languages page and text_and_images.
This documentation is pulled from the DAISY knowledge base, Benetech, and our own inhouse research and development with our Analysts that have lived experiences. Some of our guidelines will be a bit different from what you find out on the internet, as we are not creating an EPUB from scratch. We are reformatting an EPUB, so our guidelines may be slightly different.

Part of your job is to produce accessible versions of the titles you are assigned. Alt-text is an essential part of accessibility. You should be able to write Alt-text with little to no edits and feedback after 3 months of work.

It can take longer to learn how to write image descriptions than the other parts of reformatting an ebook, and we are here to help and support you on this journey. Even after you have gotten a handle on how to describe images, there will always be times when you struggle and need assistance. Go to Job Outline and Expectations for more information.

First Steps

Remove all decorative images including:

  • publisher/other logo (text equivalent = name of publisher/company)
  • decorative image (no text equivalent required)
  • author photo (no text equivalent required)

If unsure, ask in the Q and A section.

If the decorative image is a Content Break we replace it with a line. See Content Breaks for more information.
You can search for all images by using the "Find" function and search with ^g (for "graphic")

Ensure that the image (and caption if present) is set to inline with text so that the text does not flow around the image and between paragraphs (i.e. not breaking up the middle of a sentence or paragraph).

To set the wrapping style as in-line with text:

  • right click the image
  • select Wrap Text > In Line with Text

Software can only detect and properly read the Alt-text associated with an image when it is placed In Line with Text.

For large images, resize them so they fit on the page with their caption and surrounding text. See How to Resize Images in Word for how to do this.

If your document is missing images, you can extract the images from the publisher file. See the section on How to Extract An Image.

Basics: Add Alt-text and Caption to Image

Below are directions on how to insert captions and Alt-text using Microsoft Word.

For guidelines on how to write Alt-text go to the How to Write Alt-text section further down the page.

Add Captions

If a caption exists in the original ebook, then you must insert it for the corresponding image in the Word doc file. See Captions for instructions.

Add Alt-text

To add Alt-text to an image:

  1. Right click on the image
  2. Select Format Picture
  3. Click on Alt Text
  4. Enter a description in the alt text description field (leave the title field blank)

How to Write Alt-text

The following documentation will walk you through how to describe different types of images you will come across. The documentation is broken down as follows:

Alt-text is done a bit differently for Children's Picture Books and Comics. Please visit their respective pages Alt-text for Picture Books and Comic Book/Graphic Novel Description: Introduction for more information.
public/nnels/etext/images.txt · Last modified: 2021/08/30 09:52 by rachel.osolen