Contact individual Summary Print page Image not showing
I don't think you're looking at the right template.  When I press Print Summary, that's not the template that loads.

You can check which template is in use by pressing "Ctrl-U" to View HTML Source, then searching for ".tpl".  When I do that, I see templates/CRM/Contact/Page/View/Print.tpl instead.

Above the {literal} tag, I added the {debug} tag and reloaded the page in my browser.  This brought up a Smarty debug window; I confirmed that $imageURL is indeed available to this template (otherwise we'd need to add it in the corresponding PHP file).

So hopefully this is enough info to get you where you need!  Update your question if not.