How to Provide Long Descriptions for Complex Images

Question

How do I provide long descriptions for complex images to meet accessibility standards?

 

Environment

  • Web Accessibility
  • Google Gemini

 

Answer

Why Provide Long Descriptions?

Generally, for images on a web page, a text alternative is provided using the alt text. It is considered good practice to keep alt text brief and concise (think no more than 125 characters).

However, it is sometimes impossible to describe detailed images like charts, graphs, and complex maps in the recommended length for alt text. In these cases, a longer description in addition to alt text is necessary to fully communicate the information to all users.

How to Add Long Descriptions

There are a few accessible ways to provide long descriptions for complex images:

  • Text below the image: Provide the long description itself right below the image.
  • Link below the image: Provide a link to the long description below the image. Be sure the link describes the destination (e.g., "Detailed description of chart")

Using Google Gemini to Generate Descriptions

While there are multiple ways to display the text, you still have to write it. AI tools like Google Gemini can do the heavy lifting of drafting both the concise alt text and the detailed long descriptions.

Use this link to access Google Gemini. Make sure you're logged in with your GRCC employee email.

Below is an example prompt showing how to use Gemini to generate accessible text.

Example 1: Complex Image 

Prompt

I need alt text for this image used on a quiz question, but I don't want to give the answer away. Here is the question: Identify these processes encircled. The answer is dendrites. Here is the image:

A diagram of a cell with a central body and a long tail-like structure pointing downward. A prominent red circle highlights the multiple thin, tree-like branches extending outward from the main central body.

Response 

Here are a couple of options for your alt text:

Option 1: Detailed and Literal (Recommended)

"A diagram of a cell with a central body and a long tail-like structure pointing downward. A prominent red circle highlights the multiple thin, tree-like branches extending outward from the main central body."

Option 2: Concise

"An illustration of a nerve cell. A red circle

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