Its purpose is to produce enhanced images of astronomic observations through combining consecutive photographs (an image "stack") of the same scene that were taken over a short period of time. The process relies on the subject (e.g. a planet) being unchanged between photographs, so that any differences can be assumed to be random noise or atmospheric interference.
The stack of images can be in the form of individual consecutive shots or from frames of a movie camera trained on the scene.
Image of the transit of Venus, shot as consecutive photographs then processed into a single image.
Image of part of the moon, shot as a video then processed into one still image.
Cor Berrevoets (The Netherlands) began development of the program about 2001, and it was released on 19 May 2002. This initial release (version v1.0.0) had facilities for stack alignment, grading and selection of the images to be merged, and image enhancement using techniques such as wavelet processing. The program was regularly updated by its author and on 6 June 2004 a multi-lingual version was begun (v3) and the program was later available in 15 different languages. To date (May 2013) the latest release is v184.108.40.206 (6 May 2011) which was contributed to by a team of 9 people.
^Mobberley, Martin (2006). Lunar and Planetary Webcam User’s Guide. Springer. p. 89. "The package that emerged head and shoulders above the compeditors was written by a Dutchman, Cor Berrevoets and is called Registax."
^Zawodny, Joe (2008-11-15). "Joe Zawodny » RegiStax vs AviStack". Retrieved 2013-05-26. "RegiStax has been around for a long time and is probably the single reason why amateur astronomy has made huge strides in the last several years."