When it comes to editing images, there are massive apps like Photoshop with which you can do almost anything you can think of. But if all your photos need is a little retouch here and there, you may as well use a lighter alternative like StylePix.
With StylePix you can fix, optimize and edit photos in a simple way. The program's interface is not very attractive, but it does include some surprisingly powerful features such as support for layers, a handy history window, ability to process several images simultaneously and a wide array of special filters and effects.
StylePix lets you browse the content of your photo folders, but it's probably much more comfortable to see them in full screen (F11) or even make use of the Slideshow functionality included in the program (F5). On the downside, StylePix doesn't support as many formats as you would expect from such a complete app.
With StylePix you can browse, view, optimize and edit your photos in a very easy way.