You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allimages aicontinue="20151225110215|Vectrex_MAME.jpg" />
  </query-continue>
  <query>
    <allimages>
      <img name="Creative_style.jpg" timestamp="2016-01-05T20:36:58Z" user="Muller8" url="https://events.ccc.de/congress/2015/wiki/images/8/86/Creative_style.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Creative_style.jpg" ns="6" title="File:Creative style.jpg" />
      <img name="InfoBlatt.pdf" timestamp="2016-01-02T20:33:42Z" user="HS" url="https://events.ccc.de/congress/2015/wiki/images/8/8f/InfoBlatt.pdf" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:InfoBlatt.pdf" ns="6" title="File:InfoBlatt.pdf" />
      <img name="Cch_to_fhb_centro_path_map.jpg" timestamp="2015-12-27T07:03:19Z" user="Algoldor" url="https://events.ccc.de/congress/2015/wiki/images/c/ca/Cch_to_fhb_centro_path_map.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Cch_to_fhb_centro_path_map.jpg" ns="6" title="File:Cch to fhb centro path map.jpg" />
      <img name="Ccc_pdf_fuzzinozer.pdf" timestamp="2015-12-27T06:54:46Z" user="Bobim6" url="https://events.ccc.de/congress/2015/wiki/images/8/8d/Ccc_pdf_fuzzinozer.pdf" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Ccc_pdf_fuzzinozer.pdf" ns="6" title="File:Ccc pdf fuzzinozer.pdf" />
      <img name="Findfindit.pdf" timestamp="2015-12-26T19:39:23Z" user="Jorges" url="https://events.ccc.de/congress/2015/wiki/images/c/cd/Findfindit.pdf" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Findfindit.pdf" ns="6" title="File:Findfindit.pdf" />
      <img name="ElectronigGeekBag3.jpg" timestamp="2015-12-26T02:39:33Z" user="Teschi" url="https://events.ccc.de/congress/2015/wiki/images/d/de/ElectronigGeekBag3.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:ElectronigGeekBag3.jpg" ns="6" title="File:ElectronigGeekBag3.jpg" />
      <img name="ElectronigGeekBag2.jpg" timestamp="2015-12-26T02:37:52Z" user="Teschi" url="https://events.ccc.de/congress/2015/wiki/images/e/ef/ElectronigGeekBag2.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:ElectronigGeekBag2.jpg" ns="6" title="File:ElectronigGeekBag2.jpg" />
      <img name="ElectronigGeekBag1.jpg" timestamp="2015-12-26T02:35:45Z" user="Teschi" url="https://events.ccc.de/congress/2015/wiki/images/2/21/ElectronigGeekBag1.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:ElectronigGeekBag1.jpg" ns="6" title="File:ElectronigGeekBag1.jpg" />
      <img name="Food_hacking_base_2015_and_beyond_lightning_talk_32c3.pdf" timestamp="2015-12-25T22:30:23Z" user="Algoldor" url="https://events.ccc.de/congress/2015/wiki/images/1/14/Food_hacking_base_2015_and_beyond_lightning_talk_32c3.pdf" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Food_hacking_base_2015_and_beyond_lightning_talk_32c3.pdf" ns="6" title="File:Food hacking base 2015 and beyond lightning talk 32c3.pdf" />
      <img name="Supporter-ecix.png" timestamp="2015-12-25T17:31:11Z" user="Noc" url="https://events.ccc.de/congress/2015/wiki/images/1/12/Supporter-ecix.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Supporter-ecix.png" ns="6" title="File:Supporter-ecix.png" />
    </allimages>
  </query>
</api>