FastCV Computer Vision - FastCV will enable you to add new user experiences into your camera-based apps like:
Accord.NET Framework - Machine learning, computer vision and statistics framework for .NET
BoofCV - BoofCV is an open source library written from scratch for real-time computer vision.
OpenCV - OpenCV is the world's biggest computer vision library
SimpleCV - SimpleCV is an open source framework for building computer vision applications.
LeptonicaSharp - C# Wrapper for the Leptonica Library Version 1.77