Finally, after a lot of homework avoidance, I have put virtual pen to paper on the topic of DSO processing. I have always dreaded doing this article, but knew that sooner or later I would have to do it. DSO processing is as much art as science. No tutorial will ever be complete - there are such a myriad of tricks and tips that can be employed, it is impossible to cover all of them in one short article.
Also, no article is a substitute for experience. Several aspects of processing rely on the astronomer's hand, eye and personnal preferences. Aspects such as colour balance and histogram adjustments will be a source of endless debate. There is no right way, there are only opinions.
I have decided the only way I can approach this article is to take us through my typical processing session. My images are principly captured using an SC3 modified toucam webcam. The original CCD Sensor has been changed for an ICX424 black and white sensor. To capture colour, I use a set of Astronomik RGB filters. I do not normally use an IR filter on deep sky objects. My images are captured into an AVI using k3ccdtools. This software saves a handy log file for each object.
I do not own a filter wheel. I have to remove the camera from the telescope and change the filter by hand. This introduces some rotation between the RGB and L frames. Typically I will expose as deep as I can for as long as I can with no filter for my lumineance (L) frame, and then take about a dozen frames with each colour filter. This results in four AVI files. L, R, G and B. As I capture each file I rename it to indicate the filter used. Its very tricky to decide which one is which after the event!
We start the story with these 4 AVI files sitting on our computer. If we have a dark frame AVI or a flat frame, we can use that too.