Image selection based on type using dbtoepub

I am using docbook, xsltproc, dblatex, and dbtoepub (epub not epub3) with a standard Ubuntu distribution
https://packages.ubuntu.com/bionic/all/docbook/filelist
https://packages.ubuntu.com/bionic/all/docbook-xsl/filelist
https://packages.ubuntu.com/bionic/all/dblatex/filelist
https://packages.ubuntu.com/bionic/all/dbtoepub/filelist
and I am trying to produce manuals in HTML, PDF, and EPUB format. 

I want to select the image to use depending on the output format as follows
<figure id="tiling" float="start">
  <title>Multidimensional tiling for temporal floats.</title>
  <mediaobject>
    <imageobject><imagedata format="PDF" scale="75" fileref="images/tiling.pdf"/></imageobject>
    <imageobject><imagedata format="SVG" scale="75" fileref="images/tiling.svg"/></imageobject>
    <imageobject><imagedata format="PNG" scale="75" fileref="images/tiling.png"/></imageobject>
  </mediaobject>
</figure>

This works well for producing HTML and PDF format but dbtoepub does not understand this and does not include any image. I have also tried with roles (e.g. role="html" or role="dblatex") but also does not work with dbtoepub.

Any way to solve this ?

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Prof. Esteban Zimanyi
Department of Computer & Decision Engineering  (CoDE) CP 165/15    
Universite Libre de Bruxelles            
Avenue F. D. Roosevelt 50                
B-1050 Brussels, Belgium                 
fax: + 32.2.650.47.13
tel: + 32.2.650.31.85
e-mail: 
Internet: http://cs.ulb.ac.be/members/esteban/
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