Quick answer
Images help explain and show content, but very large files may take more data and time to reach visitors. If a meaningful image lacks suitable alternative text, someone using a screen reader may lose part of the information. Not every image needs the same change: its role and context matter.
What to look at
Check whether a needed image is available, whether its size suits how it appears, and whether its alt attribute conveys the information needed when the image has meaning. A decorative image may intentionally need an empty alt: the technical fact alone cannot decide.
How important is it?
A missing resource may remove content from a page; a heavy one may affect loading; unsuitable alternative text may hinder understanding. The guide shows Moderate, but TrustyRunner does not measure visitors' perceived load time or full accessibility here. Prioritize images that matter to that page.
What TrustyRunner observes
TrustyRunner distinguishes where an image is referenced in a page from the image file it can acquire. For the reference it may read alt, lazy loading, and declared or observable dimensions; for the file it checks the HTTP response, acquired byte count, format, and intrinsic dimensions.
The two parts have separate limits: finding a reference does not mean acquiring the file, and acquiring a file does not prove every use of it on the site was found.
How to read the result
- HTTP 400 or higher for a file: check the exact code. A 403 or 429 does not prove the file does not exist.
- File over 500 KiB, image much larger than its observed use, or missing/empty
alt: these are findings about collected facts to assess in context. - File over 250 KiB, older raster format, generic name or
alt, non-lazy loading, non-image file, or incomplete inspection: these are review signals, not mandatory fixes.
A result with no findings is conclusive only if both page references and file acquisition/inspection are complete within their separate limits. If only part of a file was acquired, its observed size does not prove it is small.
What to do
Start with images that matter to the content. Investigate an access error before replacing a file; assess size and format in light of its use; provide relevant alternative text when an image conveys information. Test the page after a change, without applying the same rule to every image.
Limits of this check
TrustyRunner does not measure real performance, Core Web Vitals, alternative-text quality, full accessibility, or search-engine impact. It does not prove every image was assessed, and an HTTP error for a file does not always prove visitors see a missing image.
Verify with a new scan
A new scan can compare references and files reached again, including observed size, format, and availability. Understanding the effect on visitors requires separate checks of the page and its accessibility.