Images without alt text - WCAG 1.1.1
what a screen reader does instead, and the hand-fix
This is the finding that costs the most reader minutes and the one that no tool can close on its own. An image with no alt attribute is announced by its file name, so a reader hears something like "image 0 0 4 dot j p g", which tells them nothing except that they have missed something.
The hand-fix
Open the XHTML file, find the img element, and add an alt attribute with a true description, or an empty one if the image is genuinely decorative. Both forms below are correct EPUB 3.
<img src="images/fig-03.jpg" alt="A hotbed in cross-section: manure below, soil above, glass lid tilted south." /> <img src="images/ornament.png" alt="" role="presentation" />
SVG images
An inline SVG is not an img. Give it role="img" and an aria-label, or a title element as its first child. Reflow writes the role and aria-label form.
What Reflow does
Drafts a description for every image, flags the ones it is unsure about, and writes only what you approved. A flagged image is left exactly as found until you resolve it.