CCDStack

CCDStack is an extremely complex and powerful piece of software designed from the ground up to provide its users with all the available resources for stacking and, ultimately, analyzing and viewing CCD (short for charge-coupled device) images.
The application is capable of working on a wide array of versions of Windows, however, please note that the 32-bit version is limited to around 1 GB of RAM, which might prove to be quite insufficient for most stack-related procedures.
It can be deployed just like any other app on any computer, just as long as the presence of .NET Framework 4.0 or newer is ensured. The interface is not exactly impressive, with a fairly outdated look by modern standards, however, it does a good job at allowing users access everything the app has to offer.
Some of the provided features for processing and assembling complex CCD astronomical images include frame calibration (dark, flat, and bias), star bloom removal, image alignment and registration, re-sampling of registered images, image normalization, advanced data rejection.
Users are also provided with the tools for combining images, for removing gradients, real-time DDP display, for deconvolution and sharpening, as well as full LRGB color tweaking capabilities.
For more information, users are urged to check out the app's online help section which bundles everything from documentation files, processing tutorials, a video overview, as well as some very handy sample files.

Limitations in the unregistered version