Chrome Extension Source Viewer (CESV) is a free Chrome extension which, as its name suggests, makes it easy to view the source - and embedded images - of Chrome or Firefox extensions.

Once installed, CESV displays a "CRX" icon in the address bar whenever it can be used. Just browse the Chrome store or addons.mozilla.org, find an extension, click the icon and its source is displayed in a new tab.

This opens with two panes. Extension files are listed on the left, and clicking any of these displays its code - nicely formatted and with syntax highlighting - on the right.

Developers can filter these files to explore the code, mark-up, locales and other files, run regular expression searches to find the content they need, or save the source locally as a CRX or ZIP file.

Even if you're not interested in the low-level technicalities, you can still use CESV to find images, view and maybe save them locally.