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="20091117102533|Jabbim-client-sd-simple.png" />
  </query-continue>
  <query>
    <allimages>
      <img name="04_psi_skype_account.png" timestamp="2013-09-30T16:04:15Z" user="Lray" url="https://www.jabber.cz/w/images/3/33/04_psi_skype_account.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:04_psi_skype_account.png" ns="6" title="Soubor:04 psi skype account.png" />
      <img name="03_psi_skype_services.png" timestamp="2013-09-30T16:04:05Z" user="Lray" url="https://www.jabber.cz/w/images/f/fa/03_psi_skype_services.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:03_psi_skype_services.png" ns="6" title="Soubor:03 psi skype services.png" />
      <img name="02_psi_general_menu.png" timestamp="2013-09-30T16:03:57Z" user="Lray" url="https://www.jabber.cz/w/images/f/f9/02_psi_general_menu.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:02_psi_general_menu.png" ns="6" title="Soubor:02 psi general menu.png" />
      <img name="01_psi_start.png" timestamp="2013-09-30T16:03:44Z" user="Lray" url="https://www.jabber.cz/w/images/f/f3/01_psi_start.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:01_psi_start.png" ns="6" title="Soubor:01 psi start.png" />
      <img name="Silper_10k_19_11_2011.jpg" timestamp="2011-11-19T12:09:16Z" user="Frenky" url="https://www.jabber.cz/w/images/6/66/Silper_10k_19_11_2011.jpg" descriptionurl="https://www.jabber.cz/wiki/Soubor:Silper_10k_19_11_2011.jpg" ns="6" title="Soubor:Silper 10k 19 11 2011.jpg" />
      <img name="Jabiru3.png" timestamp="2011-02-13T12:37:48Z" user="Teiwaz" url="https://www.jabber.cz/w/images/a/ac/Jabiru3.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:Jabiru3.png" ns="6" title="Soubor:Jabiru3.png" />
      <img name="Jabiru2.png" timestamp="2011-02-13T12:34:40Z" user="Teiwaz" url="https://www.jabber.cz/w/images/3/30/Jabiru2.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:Jabiru2.png" ns="6" title="Soubor:Jabiru2.png" />
      <img name="Jabiru1.png" timestamp="2011-02-13T12:31:48Z" user="Teiwaz" url="https://www.jabber.cz/w/images/b/b9/Jabiru1.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:Jabiru1.png" ns="6" title="Soubor:Jabiru1.png" />
      <img name="Silper.jpg" timestamp="2010-03-20T12:31:24Z" user="Frenky" url="https://www.jabber.cz/w/images/0/06/Silper.jpg" descriptionurl="https://www.jabber.cz/wiki/Soubor:Silper.jpg" ns="6" title="Soubor:Silper.jpg" />
      <img name="Jabbim-client-sd-extended.png" timestamp="2009-11-17T10:32:54Z" user="V6ak" url="https://www.jabber.cz/w/images/c/c2/Jabbim-client-sd-extended.png" descriptionurl="https://www.jabber.cz/wiki/Soubor:Jabbim-client-sd-extended.png" ns="6" title="Soubor:Jabbim-client-sd-extended.png" />
    </allimages>
  </query>
</api>