Castrator will very likely no longer be updated

Castrator, a tool for cropping planetary videos to uncompressed new videos, is no longer officially supported - as I'm too busy with AutoStakkert! - but the software can still be downloaded of course. If you are looking for a much more modern tool to pre-process planteary recordings - with way more possibilities - please also have a look at the Planetary Imaging PreProcessor software (PIPP) (external link).


  • Crop and center planetary avi files (color and grayscale)
  • Save disk space
  • Facilitate fast processing
  • Easy and fast batch processing
  • Can handle both color and grayscale Y8 input and output
  • Lossless output in Y8 or DIB avi

A few years ago - when I started my astronomy hobby - I noticed that planetary recordings take up a lot of space on your hard-drive. Most of that space is actually not needed - because the planet only takes up a small portion of the recording, and that bulk data also makes processing unnecessarily slow. There are several existing solutions that all have their weak points.

  • Crop during recording. This could be a very nice solution, but there are not many programs that can do this properly. Most of the capturing programs that can crop during recording, can only use a fixed cropping size that doesn't follow the planet around on the screen. For me that is not good enough, because my mount is not very sturdy, and I have to continously make movement corrections to keep the planet in the recording area. FireCapture is the only capturing program that I know of that can follow a planet during recording, and crop the avi accordingly. But FireCapture needs a fast computer (one that I don't have), and I haven't been able to reliably track a planet throughout a recording so far. The program does show a lot of promise though.
  • Other cropping tools that save the frames of an avi-file to image files. This leaves you with a LOT of files on your hard-disk which is not very fast and practicle to handle. Imagine taking 100 planetary avi's on a clear night - not uncommon for me - and then imagine almost half a million of files sitting in different folders for every avi one. It would be much easier to simply have 100 new avi cropped and centered planetary avi files, sitting around in the same folder.
  • Lossless compression. The processing will be relatively slow (decoding/encoding takes time), and the compression ratio is often not very high.
  • Lossy compression. The processing will also be slow, but the compression ratio will be a bit higher. But as the name implies, information is actually lost during encoding, and that information is lost forever.

All these reasons made me want to developed my own cropping and aligning program, called Castrator. Castrator produces uncompressed lossless (Y8 or DIB) output that still saves a lot of space on your hard-drive. You can select many avi files in one go, and simply come back a few minutes later to view the results. You can process these results - in the form of a new avi file - any way you like in existing software programs, but I suggest you have a look at AutoStakkert! when it will be released.


The following list contains known issues and/or things that I should do for a future release.

  • Auto select planet size
  • Ignore incomplete frames (with only a partial or no planet visible)


Although great care has been taken to ensure that the software works without problems, I cannot garantuee that it actually does. Castrator was only tested under Windows XP and Windows Vista. If you have any problems, feature requests or other questions about Castrator, you can either go to my forums and drop a message, or contact me directly. Please note that I'm a fulltime college student, and simply don't have time to work as much on this project as I would like.

You can download the latest version (v0.0.1.12) here (updated March 12, 2012)

An older version of Castrator (v0.0.1.9) can be downloaded here