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Posts: 1
Registered: ‎03-09-2011

What does "invalid images" mean?

My epub passes all preflight checks. It fails with:


Your EPUB failed to validate for the following reason(s):
 * Contains invalid images.



All my images are in OEBPS/images, they are pngs, they are referenced by OEBPS/content.opf as being in images, and they're all there with full permissions. Are there any specifications that lulu has? Any more informative logging than "Contains invalid images"?