Information & AI · Information evaluation and accessibility
Make information usable: images, color and error messages
Information visible on a screen does not reach every person in the same way. People who do not see an image, distinguish its colors or use a mouse still need to understand its meaning and what to do next. Consider the information's purpose and available routes, not only its quantity.
Using WCAG 2.2 as a reference, this guide connects image alternatives, color cues and input errors. The goal is not to describe every visual detail. Begin by providing information that lets people achieve the same purpose through an appropriate form.
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Explain an image according to its role
An informative image needs a text alternative serving its purpose. A product photograph and an image button that submits a form do different jobs. For the button, a useful name conveys the action rather than only listing colors and shapes.
Pure decoration can be handled without repeatedly announcing a long description. Important information or controls should not be classified as decorative merely to avoid writing an alternative. Decide why the image is present before choosing what a user needs to receive from it.
Do not leave meaning to color alone
Turning an incorrect input field red can fail to communicate the location and reason to someone who does not distinguish that color. Supply text, symbols or another suitable non-color cue. Color can help, but should not be the only route to the meaning.
Apply the same principle to legends and status indicators. Instead of identifying completed and incomplete items only by blue and green, include the status names. Evaluate how the distinction can be read, rather than assuming a more vivid appearance makes it more informative.
Make an error understandable enough to correct
A form that says only error leaves the user uncertain about what to change. When an input error is detected automatically, identify the affected item and describe the error in text. A missing name and an incorrectly formatted date call for different explanations.
Relating labels, instructions and error descriptions helps people move from an input's purpose to the place needing correction. Visual proximity alone does not ensure that assistive technology can perceive those relationships. Consider both the displayed information and its understandable structure.
TRY & READ
Check your understanding with examples
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Example 1 · Information evaluation and accessibility
What is a basic purpose of alternative text for an informative web image?
Always encrypt the image file
Convey equivalent information when the image cannot be seen
Always sharpen the image
Necessarily improve search ranking
Read the answer and explanation
Answer: Convey equivalent information when the image cannot be seen
Write alternatives according to the image's purpose rather than automatically listing every visual detail.
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