Way back in 2011 I was bitten by the astrophotography bug and enjoyed taking star trail photography. For those who aren’t aware what that is, here is a brief summary from wikipedia:
A star trail is a type of photograph that utilizes long-exposure times to capture the apparent motion of stars in the night sky due to the rotation of the Earth. A star trail photograph shows individual stars as streaks across the image, with longer exposures resulting in longer streaks. Typical exposure times for a star trail range from 15 minutes to several hours, requiring a ‘bulb’ setting on the camera to open the shutter for a longer period than is normal.
— Wikipedia (2016)
At the time there was no free software for the mac so I wrote a plugin for the free image program GIMP. This got a reasonable amount of use by others but not long after a few more fully featured software became available, I ahem found ahem Adobe Photoshop (and now pay for it) and the plugin fell by the way side.
Where am I going with this? Well being an open source project on github other users are able to contribute fixes and new features. This week exactly this happened. The new change adds a basic method to remove sky glow from the image as well as a few other minor bits.
The incredibly well named gimp-startrail-compositor 1.8 is available on github.