asciidoc: how to add callouts asciidoc to image

How can i add callouts to images like in docbook? See an example here: http://norman.walsh.name/2006/06/10/imageobjectco

The callout points can be drawn on the image, but when i try to generate document from this:

image::img/stg.png[width=400,align="center"]
<1> Blabla.
<2> Foobar.
<3> Aknathnaratnathgarat.

... it drops an error:

asciidoc: WARNING: manual.adoc: line 580: no callouts refer to list item 1
asciidoc: WARNING: manual.adoc: line 581: no callouts refer to list item 2
asciidoc: WARNING: manual.adoc: line 582: no callouts refer to list item 3

Solution

It's important to understand that asciidoc uses docbook, looking for it in docbook I just found out how to do this:

++++
<mediaobjectco> 
  <imageobjectco>  
    <areaspec id="map1"  
              units="calspair">  
      <area linkends="callout1"  
            coords="1000,5000 6000,8000"  
            id="area1"/>  
    </areaspec>
    <imageobject>
      <imagedata fileref="images/notredame.png" />
    </imageobject>
    <calloutlist>
      <callout arearefs="area1" 
               id="callout1">  
        <para>My only callout</para>
      </callout>
    </calloutlist>
  </imageobjectco>
</mediaobjectco>
++++

You can copy and paste in asciidoc and it will work (the ++++ operator let you put docbook code inside asciidoc). Of course you will have to have the image at images/notredame.png to work, I have used this image.

To understand more look for docbook documentation:

http://www.sagehill.net/docbookxsl/Imagemaps.html (this example was extracted from there)
http://www.docbook.org/tdg/en/html/callout.html
http://www.sagehill.net/docbookxsl/PrintIcons.html

NOTE: Asciidoc uses docbook 4.5, when looking at documentation skip 5.0 tags.

From time to time is need this feature in my books, but I end up puting a label in the image (like mapa_a.png and this one mapa_b.png), and put them side by side in a table with inline image. You can see inline images in this file, find for image:images/cap4).