Images and Accessibility in EPUB Conversion

How images are handled during conversion

Every embedded image, regardless of source format (PNG, JPEG, or JPEG 2000), is normalised to sRGB JPEG using MozJPEG encoding, at an adaptive resolution — 300 DPI for standard page sizes, 200 DPI for larger pages. CMYK images from print-ready PDFs are converted to sRGB automatically.

AI alt-text generation

By default, interior page images get a generic alt text of "Page N". On Pro and Publisher plans, AI alt-text generation using GPT-4o Vision is available and only runs when you explicitly request it.

Metadata by conversion mode

Advanced Live Text has a real, searchable text layer and EPUB Accessibility 1.1 metadata, but its fixed page layout means full WCAG/EAA conformance is never claimed for it. Reflowable EPUB can carry a full WCAG 2.1 AA conformance claim when its alt text is complete. Visual Perfection is image-based and carries no text-based accessibility claim.

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