IC Imaging Control -- image acquisition ActiveX  
   IC Imaging Control is an image acquisition SDK that works with any video source compiling to Microsoft's WDM specification. As an ActiveX and C++ Class Library, IC Imaging Control allows programmers to create image acquisition applications with only a few
   http://www.imagingcontrol.com/

LEADTOOLS DeveloperToolkits for Image Processing  
   LEADTOOLS Raster Imaging Engine forms the basis for most of the imaging technology found in LEAD Toolkits, encompassing file import/export, image acquisition, image processing, display, and database connectivity.
   http://www.leadtools.com/home2/VertMkts/RasterEngine.htm

ImLib3D  
   ImLib3D is an open source C++ library for 3D (volumetric) image processing. It comes with an optional viewer that features multiplanar views, animations, vector field views and 3D (OpenGL) multiplanar.
   http://imlib3d.sourceforge.net

Image Precessing: Algorithms  
   Links to many different image processing algorithms
   http://www.efg2.com/Lab/Library/ImageProcessing/Algorithms.htm