Imagus is a browser extension that is able to enlarge thumbnails, and show images/videos from links in a pop-up without leaving the page. URL for sharing: https://tiny.cc/Imagus
The archived old home-page (with all the comments) can be found here.
Install the latest version for
To install on Opera 12, download the extension file and drop it into the browser window.

In Opera 15+, the extension must be manually enabled in the Extension manager (Ctrl+Shift+E) after install.

Opera 12 12
Opera 15+ 15+

Safari 5.1+
Choose Open when the download dialog appears, then Install.
Maxthon 4+
MS Edge
This video will show you how to install it on MS Edge (versions available only on Windows Insider).
	+ Added feature
	* Improved/changed feature
	# Bug fixed

	(vw) - viewer, (hz) hover-zoom, (op) - image opening, (sv) - sieve, (prf) - preferences

		opr: Opera 12
		ffx: Firefox, SeaMonkey (possibly other Gecko based browsers)
		chr: Chrome (or other clones of Chromium, like Vivaldi, Opera 15+, Yandex Browser...)
		sfr: Safari 5.1+
		mxt: Maxthon 4+
(click the date to expand/collapse)