You could use IrfanView, a FREE program that is used by lots of folks,a nd is more than just a simple viewer. It is available from the link below.
If you install it, and got to Options - Properties, and choose the Misc2 tab, you can put in an External Editor in the box there (use browse button). Then scroll through the images in a folder or whatever. You can hit the F key to toggle between full screen, and full size (really big). When you see one you want, you can hit Shift-E and the External Program will start up.
http://www.irfanview.com