I have finally found the time to finally release my library for creating procedural textures called JTexGen under the LGPL license. It is a framework for rendering and viewing procedural textures which you can then use as images, backgrounds and textures for modelling. Because the textures are procedural, you can ramp up the resolution of the image to get increased detail without getting blocky artifacts.
The source code for the above images is included in the distribution and also discussed in the reference documentation. These images are reproduced untouched after being generated using a few lines of Java code.
The distribution contains the usuals (source, a jar, javadocs can be built in maven) and also a reference manual in pdf and html format. The reference manual describes what procedural textures are and how to use the framework to create them. The library itself is thread safe, and uses multiple threads to render the images.
The files can be downloaded from Project Kenai, and contains nearly 100 different textures and signals you can use.