Digital Invisible Ink Toolkit 1.5
Digital Invisible Ink Toolkit provides a simple tool that can hide a message inside a 24-bit colour image.
There are four highly customisable algorithms in the tool, as well as an open-source implementation of RS Analysis (an extremely good steganalysis method). The tool has the additional advantage of being able to simulate hiding - so you can get an accurate map of where the information is hidden.
The compiled version can be run by simply double clicking the .jar file, or by running at a command line with the following options (you will need to run at the command line if you are using big pictures, such as those greater than 500x500 pixels or it will run out of memory):
java -jar -Xmx512m diit_1-1.jar
Where -Xmx512m tells the virtual machine to use 512MB of physical RAM (at most) - please change to suit your own machine specifications.