I'm trying to do something similar for my page, using XSL instead of a calculated column. Basically I'd like to access the actual image URL (instead of the MakeThumbnail string) so that I can have the image call a popup of a larger version from the thumbnail. Here's what I have so far:

function popup(target) {
 window.open(target, "Closeup");
}

              <script type="text/javascript">
                source="<xsl:value-of select="udt:Photo1_UDT_Original" />";
              </script>
                 <a href=" popup(source)">
                   <xsl:value-of select="udt:Photo1" disable-output-escaping="yes" />
                 </a>

These are just excerpts from the larger XSL file, with the lines in question. I think the problem is with the Photo1 XSL call, I've tried all of the variants listed here and none of them have worked. Currently, nothing is getting stored in the "source" variable, so nothing gets passes to the function.

Does anyone have any suggestions?

That helped, thanks!

It's still not quite working, but that's entirely due to my own programming, as the value is getting stored now.

That also helps, thanks you!

Only things were I had to change the spelling of "original" again ;)
and also, as written above, the link gave me a full URL with the word "popup()" at the end. So I changed it to popup(<xsl....

The link is displaying correctly (example: " popup(photo.jpg)"), now I just have to figure out what else is breaking. I strongly suspect that it's due to the fact that my users have been putting spaces in their photo names, which is confusing javascript.

Thanks again!