Skip to content
EPUBCheck · Images, audio and media overlays

EPUBCheck MED-004: image header looks damaged

Updated:

EPUBCheck MED-004 is an error message: “Image file header may be corrupted.” An image file's header looks damaged, so the image may not display. EPUBCheck reads the first bytes of each image to check its format and size, and here they do not make sense.

The official message

Image file header may be corrupted.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

Typical causes

  • An image truncated in a copy, a download or a failed ZIP operation.
  • An image saved by a faulty tool, or a file whose extension does not match its content.

How to fix it

  1. Open the image in an image viewer: if it fails or shows only part of the picture, it is damaged.
  2. Re-export the image from its source and replace the file, keeping the same name or updating every reference to it.
  3. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

When it's not this

If the image cannot be decoded at all, EPUBCheck reports PKG-021; a wrong extension is PKG-022.

Terms used here

Other MED messages

  • MED-003 Picture "img" elements must reference core media type resources, but found resource "…" of type "…".
  • MED-005 Media Overlay audio reference … to non-standard audio type … found.
  • MED_007 Picture "source" elements must define a "type" attribute when they reference foreign resources; found resource "…" of type "…".
  • MED-008 The time specified in the clipBegin attribute must not be after clipEnd.
  • MED-009 The time specified in the clipBegin attribute must not be the same as clipEnd.
  • MED_010 EPUB Content Documents referenced from a Media Overlay must specify the "media-overlay" attribute.

Sources

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EpubCC.

FAQ

What does EPUBCheck MED-004 mean?

EPUBCheck MED-004 is an error message: “Image file header may be corrupted.” An image file's header looks damaged, so the image may not display. EPUBCheck reads the first bytes of each image to check its format and size, and here they do not make sense.

Is MED-004 an error?

MED-004 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.