The <or> tag selects files that are selected by any one of the elements it contains. It returns as soon as it finds a selector that selects the file, so it is not guaranteed to check every selector.

<fileset dir="${src}">
  <or>
    <depth max="0"/>
    <filename name="*.png"/>
    <filename name="*.gif"/>
    <filename name="*.jpg"/>
  </or>
</fileset>