Images with no alt text
Anyone using a screen reader gets nothing from an image without alt text. If it carries information that is not also in the text, that person misses it entirely.
When we count it as met
When we measure the same pages again, we find no image without an alt attribute.
How to check it yourself
Confirm it in the code: every image on the page has its alt text.
Measure it on your site
UXMachine measures it in a real browser, on desktop and mobile, together with the other checks.