# EPUBCheck MED-003: Picture img elements must reference…

Source: https://epublab.com/epubcheck/med-003/ (updated 2026-11-03)

EPUBCheck MED-003 is an error message: “Picture "img" elements must reference core media type resources, but found resource "…" of type "…".” An img element points to an image in a format that is not a core media type.

- Official message (EPUBCheck 5.4.0): Picture "img" elements must reference core media type resources, but found resource "%1$s" of type "%2$s".
- Default severity: Error

## Typical causes

- TIFF, BMP or other formats that reading apps are not required to display.

## How to fix it

- Convert the image to JPEG, PNG, GIF, WebP or SVG and update the manifest media type.

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EPUBLab.