Do your images have the markup they need?
It checks missing alternative text, dimensions and lazy loading on image-heavy pages.
What Check Engine measures
The test reads image resources on indexable pages and excludes detected beacons. An absent alt attribute with a nonempty image URL enters the missing-alt finding. Intentionally empty alt text is allowed by this presence test. At least 3 images without saved dimensions marks a page for the dimensions finding. A set of at least 8 images with none marked lazy produces the lazy-loading finding. These are separate conditions with separate affected page sets. For example, 3 images with no recorded dimensions are enough for the dimensions finding.
The check reads image addresses and markup. It does not look at the picture to identify its subject. Review the image's purpose before deciding what alternative text it needs.
How to read the result
Missing alt attributes and dimensions are medium severity. Lack of lazy loading on image-heavy pages is low. A present attribute does not prove that its text is useful or that an image's dimensions are correct.
Why it matters
Image markup can supply a text alternative and reserve space before loading. Those jobs differ from choosing when to fetch an image, which is why the code reports them separately rather than describing every image issue as a single optimisation.
How to fix it
Give meaningful images useful alternative text and decorative images the appropriate empty attribute. Set correct dimensions or a suitable reserved aspect ratio. Apply lazy loading to images that should wait, reviewing prominent content separately. Check a real page after editing shared image components so that the fix does not hide useful descriptions or delay an important image.
What we found in field audits
Problems in On-page SEO were found on 14 of the 14 sites we audited. These are area totals. Read the field-audit method.
Method note
backend/seo_engine/checks/onpage.py, images, revision 0bb8e8d3.
Common questions
How many images without dimensions trigger the image-markup finding?
At least 3 images lacking saved dimensions are enough. This count is separate from the lazy-loading test.
Does an intentionally empty alt attribute count as missing alternative text?
No. Intentionally empty alt text passes the presence test. A person still needs to decide whether the image is decorative.
How many images are needed before absent lazy loading is reported?
The page needs 8 images or more, without any marked lazy. Review prominent images before delaying their loading.