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SigmaCombine Overview

SigmaCombine is a re-usable, scriptable component that enables FITS images to be combined using advanced statistical methods. Inspired by programs such as Ray Gralak's "Sigma" and Adam F. Block's CCDSoft plug-in, Software-y-Ddraig's rendition is different because it is scriptable, open-source and compatible with Microsoft's .NET development tools. The code and internal data structures are optimized for multi-threading, to take advantage of multi-CPU systems and Intel CPUs with Hyperthreading.

SigmaCombine uses Matthias Busch's FITS.Image driver as its back-end file I/O engine. Written as a .NET assembly, it also exposes a COM interface, so that it can be instantiated from scripts, VB6 applications, even an excel spreadsheet! The SigmaCombine component exposes a set of simple methods and properties that make it easy to perform sophisticated combination of both light frames and reduction frames, without having to know anything about the internals of FITS files.

The component takes as input three pieces of information:

Collection of file names

Simply a collection of strings containing the fully qualified path and file name of each file to be included in the combined image.

High Reject Threshold

Expressed in standard deviations, pixels having a value above this threshold will be discarded and not used in the combined frame. This is useful for removing items such as cosmic ray hits.

Low Reject Threshold

Similar to the high threshold, also specified in standard deviations. Picels having a value lower than this threshold will also be discarded.

SigmaCombine is currently in development and a pre-alpha proof-of-concept prototype has been produced. The finished component will form an integral part of the DarkManager application and will enable it to automate the production of master frames. The component will be released as open-source and donated to the ASCOM initiative.