gThumb is a popular image viewer application for Ubuntu. It is also one of the few programs that can be used to view WebP image files. However, the gThumb version that ships in most Ubuntu distributions is very old and does not yet have this support.
To update gThumb, add the ppa:webupd8team/gthumb repository and reinstall the app:
$ sudo add-apt-repository ppa:webupd8team/gthumb $ sudo apt-get update $ sudo apt-get install gthumb
You should be able to view WebP files now using gThumb.
Tried with: gThumb 3.1.2 and Ubuntu 12.04