Writing Image-Alternative Decisions by Purpose
Writing Image-Alternative Decisions by Purpose records a distinct W3C-supported accessibility writing task while keeping implementation mechanics outside the writing guidance.
Choose the image alternative from what the image is doing in context: convey information, perform a function, reproduce text, present complex information, repeat nearby text, or decorate.
Key details
Important caveats
Scope Boundary
The same image can need different treatment in different contexts; this guide is a decision framework, not a fixed alt-text phrase generator.
Further guidance
Content
Decide what text alternative to write only after determining whether the image is informative, functional, text-bearing, complex, redundant, or decorative in that specific context.
Practical Application
Classify the image by what it does in this context before writing anything: informative content, functional control, text-bearing image, complex information, redundant illustration, or decoration.
Purpose
Purpose-first classification prevents authors from writing literal descriptions when the image instead needs a functional label, equivalent information, or no spoken alternative at all.
Reader Check
If the same image appeared somewhere else, could its purpose change enough that the appropriate alternative would also change?
Worked Example
A magnifying-glass icon inside a search button needs a functional label such as the action “Search”; the same icon used only as decoration beside a heading may need no spoken alternative.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- An alt Decision Tree — W3C WAI Images Tutorial (opens in a new tab)World Wide Web Consortium (W3C) Web Accessibility Initiative · W3C WAI decision guidance for choosing text-alternative treatment according to image purpose and context.