An image accessibility review needs to examine what an image does on the page, then decide whether its information or function is available in an appropriate text alternative. An automated report that finds an alt attribute cannot determine whether the words explain the right thing. Conversely, a decorative image can appropriately have an empty alternative.
This guide provides a context-based workflow for checking photos, linked images, icons, screenshots, and complex graphics. Include the selected pages and states in the audit scope, and combine the review with the manual and automated testing plan.
Start with the image's purpose in its current context
Non-text Content, SC 1.1.1, is a Level A requirement for appropriate text alternatives, with provisions for different kinds of non-text content. A review should therefore ask which information or function needs an equivalent, rather than assigning the same description to every appearance of an asset.
WAI's Images Tutorial distinguishes informative, decorative, functional, and complex images. Its alt decision tree helps authors choose an approach for HTML images based on their use.
For example, a venue photograph may simply decorate an appointment introduction. On a page describing step-free access, the same photograph might provide information about the entrance. Record the page purpose and neighboring content before judging the alternative. The filename and the asset's appearance alone do not settle that choice.
Build an image review inventory that includes states
List images encountered in important tasks, including images revealed in expanded panels, galleries, error states, and confirmations. Identify meaningful icons and graphics as well as large photographs. A small image can be the only explanation of what a control does.
Use a matrix such as this fictional venue-booking example:
| Image or graphic | Purpose to investigate | Evidence to keep |
|---|---|---|
| Introductory venue photo | Decoration or information about the venue | Page context and surrounding text |
| Image-only venue link | Destination of the link | Link's accessible name and destination |
| Calendar icon | Decoration beside text or the sole control label | Control name and interaction state |
| Entrance photograph | Information about access to the building | Intended message and actual alternative |
| Availability chart | Relationships between dates and capacity | Graphic, summary, and detailed equivalent |
Keep the alternative and its implementation with the record. A note saying “description added” does not show which asset, language, or state was reviewed. If a reusable component renders an image in several contexts, inspect those contexts before approving a single shared description.
Review informative descriptions for the information that matters
Ask what a reader needs to learn from the image on this page. Then compare that information with the text alternative and any equivalent nearby text. A good description is concise enough to use while preserving the important meaning; it is not an inventory of every visible object.
For the entrance photograph, an illustrative description might be “Main entrance with a ramp to the left of the steps,” if that information is visible and relevant. “Building,” “photo,” or the camera filename would leave the intended access information unexplained. Do not invent details that the image or authoritative accompanying content does not establish.
Review generated descriptions as editorial drafts. Check their accuracy and relevance against the asset and page context. There is no universal character count that makes an alternative correct; length should follow the information needed and the way the equivalent is provided.
Distinguish decorative images from unlabeled functionality
A decorative HTML image can use alt="" so its unnecessary description is skipped. Omitting the attribute is a different implementation and can lead to an unhelpful filename announcement. Decide that an image is decorative because of its role in context, not because describing it would take effort.
For a functional image, inspect the link or button containing it. WAI's Functional Images tutorial explains that alternatives should communicate the destination or action. An image-only print button needs an understandable action, while an icon next to adequate button text may be redundant.
Test the control's complete accessible name. Multiple labeling mechanisms can create duplication or replace visible words. For an image-only venue link, verify that its exposed name identifies the destination meaningfully and that activation reaches the intended page. An empty image alternative is not enough when it leaves that control without a usable name.
Provide a usable equivalent for charts and diagrams
A chart can contain more information than a short alt description can usefully convey. WAI's Complex Images tutorial describes approaches that combine a brief identification with a more complete text equivalent, including nearby explanations or data tables where appropriate.
For the fictional availability chart, consider the questions the chart answers: which dates have capacity, which are full, and what comparison the reader should understand. A detailed equivalent should preserve the relevant values or relationships. “A bar chart showing availability” identifies the visual type without providing those answers.
Verify that the longer equivalent is discoverable from the graphic's context and usable in the tested environment. If the image represents a process, explain the meaningful sequence and branches. If an alternative is on another page, check the link and destination as part of the same review.
Treat screenshots and images of text as content
Inspect screenshots for information the article or task depends on. A screenshot used to teach a setting may need the setting name and action explained in surrounding text, rather than a dense alternative attempting to transcribe the entire application window.
When an image contains necessary words, check that an appropriate text equivalent preserves those words. Also evaluate whether text has been unnecessarily embedded in an image: Images of Text, SC 1.4.5, addresses that separate Level AA question, with customization and essential-presentation exceptions.
The WCAG definition excludes text within pictures that contain significant other visual information. A screenshot illustrating an interface is therefore not automatically an image of text simply because it contains words. Assess its actual purpose and content before deciding which requirements apply.
Keep the questions distinct. Adding an alternative can address access to information while leaving an images-of-text issue to investigate. A logo has specific considerations; its presence does not create a blanket exception for the promotional paragraph rendered next to it as an image.
Verify the output and define a clear retest
Review the rendered page and inspect how the alternative is exposed. Use the screen reader testing guide for the agreed environment, then check whether the task can be understood and completed. Automated checks can support the inventory and identify some missing attributes, while meaning still needs human review.
A fictional finding might identify the venue's image-only link, its empty exposed name, the page and state, the resulting difficulty in choosing the venue, and the expected destination information. Include the current alternative, relevant markup, and steps to reach the link. The evaluator should explain the applicable requirement rather than reporting an attribute count alone.
For retesting, repeat the same context and inspect other instances affected by a shared component change. Preserve the result in the evidence handoff, with the version reviewed and any unresolved occurrences. If a new asset changes the intended meaning, review its description again instead of inheriting approval from the previous image.
Sources and how to apply this guide
The W3C sources linked above were checked on 6 October 2026. WCAG 2.2 defines the requirements; WAI's tutorials and decision tree provide implementation guidance. The venue examples and inventory are OnChange's practical suggestions, not findings about an actual venue or a complete conformance assessment. Use the examples to make the purpose, evidence, and retest decision explicit.