An unofficial, free implementation of the Java 3D API vecmath library is available online. There is an incredibly thorough collection of links to free software and code on the web. The collection is also grouped by operating system . Image Manipulation Netpbm is a free package of file manipulation and conversion programs for a wide variety of file types and operations. The C source code can be freely used in any application.
Source code is provided.
Image Magick is one of the better free conversion and manipulation GUI-based packages available for X Windows systems and MS Windows. It comes with source code. NIH Image is a public domain image processing and analysis program. In addition to traditional image editing tools, there are other operations for working with CAT scans and MRI data. For example, there is support for measuring the area or perimeter of some piece of the image.