Xnview’s shell extension enables users to view the preview of an image by simply right clicking on the image in the context menu, Set the image as his wallpaper either centered or Best fit to desktop, Convert the image into 7 different formats ( GIF, BMP, JPG, PCX, PNG, TIF, TGA ) right from the menu’s Convert Into Option, Change the size of the preview.

Here’s a screenshot of the extension in use

XnView Homepage

The XnView Extension can be downloaded from here.