Table of Contents
Alt text, or alternative text, is essential for making scientific and technical diagrams accessible to all users, including those with visual impairments. Well-written alt text helps convey complex information clearly and accurately. Here are some valuable tips for crafting effective alt descriptions for these diagrams.
Understand the Purpose of the Diagram
Before writing alt text, identify the primary function of the diagram. Is it to illustrate a process, compare data, or show relationships? Clarifying its purpose ensures the description focuses on what is most important for understanding.
Be Concise but Informative
Use clear, straightforward language to describe key elements without unnecessary detail. Focus on the main components, their relationships, and any critical data points. Strive for a balance between brevity and completeness.
Describe Visual Elements Clearly
Include descriptions of colors, shapes, lines, and labels that are vital for understanding. For example, specify if a red arrow indicates a process flow or if a dashed line represents a boundary. Use descriptive terms that convey visual cues effectively.
Use Contextual Information
Provide context to help users interpret the diagram within the broader subject. Mention how the diagram relates to the text or the concept being explained. This helps users grasp the significance of the visual information.
Include Data and Labels When Necessary
If the diagram contains data, charts, or labels, include summaries of these elements in your alt text. For example, note trends shown in a graph or specific values on a chart to ensure the information is accessible.
Test and Refine Your Description
Review your alt text by imagining how someone with no visual access would understand the diagram. Ask for feedback from colleagues or users to improve clarity and accuracy. Updating descriptions ensures they remain effective and relevant.
Example of Effective Alt Text
For a diagram showing the water cycle, a good alt text might be: “A diagram illustrating the water cycle, showing evaporation from the ocean, condensation forming clouds, precipitation as rain, and water runoff into rivers.” It covers the main processes clearly and succinctly.