About KStarStack
KStarStack is an experiment to make a cross-platform, open source software that can stack astrophotographs.
KStarStack, as of now, is a piece of C++ code lying in the playground of KDE's SVN repository: http://websvn.kde.org/trunk/playground/graphics/KStarStack
Why KStarStack?
- Because I couldn't find a user-friendly open source, cross-platform stacking tool
- Because I wanted to stack deep-sky photographs on Linux
How do we do it?
Stacking involves quite a lot of work. Let's consider the bare minimum first:
- We start with a bunch of images of the same region of the sky, which have a lot of stars (i.e., consider photos of Deep-Sky objects to start with).
- Flat-Fielding: We then need to do some minimal processing on them to remove vignetting and make the background "flat". We could use the method Seiichi Yoshida mentions here.
- Star Detection: The images need not be aligned, so we need to find common points to align the images. For astrophotographs, these would most naturally be stars. We need a good star detection algorithm. Currently, I implement something of my own. Any help will be appreciated.
- Image Alignment: The images need to be aligned based on how well they match. I am in the process of implementing a Branch-and-Bound algorithm based on Partial Hausdorff Distance that is outlined here.
- Stacking: The pixels need to be correlated and the signal-to-noise ratio must be increased. The actual process of stacking is done by algorithms such as Kappa-Sigma Clipping.
Extensions: In the future, we could plan to implement a lot more alignment methods and stacking methods. The design must be modular to support this.
Current Status:
Currently, the flat-fielding is implemented and is working well.
The star-alignment algorithm that's currently implemented is a home-made algorithm that's terrible, to put it mildly. But it seems to work reasonably.
The branch-and-bound alignment algorithm has been written, but is not compiling and has not been debugged. I don't have much time to work on this project.
The stacking algorithm has not been implemented.
Sources:
Sources may be browsed here: [http://websvn.kde.org/trunk/playground/graphics/KStarStack]
The SVN repo can be checked out using:
svn co svn://anonsvn.kde.org/home/kde/trunk/playground/graphics/KStarStack/
The src/ directory contains the sources. main.cpp is currently redundant, and what is built is the tests in the tests/ directory. Most of the stuff right now is in a state of "ugly-hacks" with TODOs all over, and these should be cleaned up at a later stage.
Contact:
I can be contacted at akarsh DOT simha AT kdemail DOT net
I hang out on #kde-in and #kde-edu on irc.freenode.org and my nick is 'kstar'.
I'd be glad to receive any help in any of these areas. TIA.
