Flagship Lumia Windows Phone devices like Lumia 1020, Lumia 930 and Lumia 1520 already supports capturing RAW images. However, you won’t be able to edit the RAW files on your Lumia devices. There is an app called Rawer which allows you to edit raw files on your phone on the go. Now you can open them, view, check EXIF info, edit, save and share in full size. You can open files from your phone, SD card or email attachment or from OneDrive or from any other app. Once you open them, it features all the following basic edit features,
Download it here from Windows Phone Store for free.