Nokia Imaging SDK (http://developer.nokia.com/Resources/Library/Lumia/#!nokia-imaging-sdk.html) – Nokia has released a fantastic SDK for editing and filtering images on Windows Phone. It is fast, clean and extremely memory efficient. Nokia has also provided 3 great sample projects that cover a lot of the most common scenarios in which a developer might use this SDK.
Lens Sample (http://code.msdn.microsoft.com/Basic-Lens-sample-359fda1b) – The Lens Sample contains the code necessary for creating an in-app viewfinder complete with focus box UI, image capture and navigation and image storage. It’s a great starting point for anyone building an image-based application.
Windows Phone Photo Extensibility (http://code.msdn.microsoft.com/Photo-Extensibility-Sample-db289044