Ok, XnView cannot open unknown file formats, but it can open many more formats than it enables during a normal install. See the full list of file formats it is able to open here.
XnView is an excellent image viewing program that handles many graphics formats and allows numerous batch operations like: resizing, compressing, image format conversion, etc.
By default, it only supports a subset of the image formats it is capable of handling. When you try to open a format it doesn’t recognize (but very likely handles), you get the following message:
![Format of the file could not be determined. For display of less common format, the following option is available: Options>General>[x]Display all image file types](http://complete-concrete-concise.com/wp-content/uploads/2011/09/xnview-open-uncommon-file-format-1.png)
Unfortunately, it is not immediately obvious where this setting is (at least it wasn’t for me).
1) Click on Tools on the menu bar:
2) Select Options from the drop down menu:
3) Click on the General label in the dialog. Then select the checkbox next to the option Display all image file types. Then click on Ok to save the results. [image may be clicked for larger size]
