I am pleased to announce that today we have released a new tool: AdaptiveStretch. This new tool is now available to all PixInsight users as an update for all supported platforms.
AdaptiveStretch is a general contrast and brightness manipulation tool in PixInsight. It implements a nonlinear intensity transformation computed from existing pairwise pixel differences in the target image. The process can be controlled through a single noise threshold
parameter. Basically, brightness differences below the noise threshold are regarded as due to the noise and other spurious variations, and are thus attenuated or not enhanced. Brightness differences above the noise threshold are interpreted as significant changes in the image, so the process tends to enhance them. The reference documentation for AdaptiveStretch is now available online:http://pixinsight.com/doc/tools/AdaptiveStretch/AdaptiveStretch.html
and of course we also have released it as an update.
The basic algorithm has been described by Maria and Costas Petrou. 
This elegant algorithm has been implemented by PTeam member Carlos Milovic, who has made important and clever modifications to make it more efficient and versatile. Carlos has done a very nice work in the core implementation of this tool. I have revised Carlos' original implementation to optimize and parallelize all processes, and have designed and written the tool's user interface. We have introduced important new features in the interface of this tool, such as auxiliary tool windows (slave interfaces) and real-time graph generation, which we'll exploit in future versions of existing and new tools, starting from PI version 1.8.
Despite the fact that this tool seems a very simple one---it is basically a one-parameter process after all---, its simplicity is only apparent. This little tool can teach you more about the dynamics of your images than some popular, ubiquitously used applications. Enjoy!
 Maria Petrou and Costas Petrou, Image Processing: The Fundamentals, Second Edition,
John Wiley and Sons Ltd., 2010, pp. 377–382.