SimpleCV - SimpleCV is an open source framework for building computer vision applications.
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
Accord.NET Framework - Machine learning, computer vision and statistics framework for .NET
FastCV Computer Vision - FastCV will enable you to add new user experiences into your camera-based apps like:
Microsoft Video API - Automatically extract metadata from video and audio files using Video Indexer. Improve the performance of your media content with Azure.