There may be many entries regarding "Image Processing" so I'm putting a number to the title. I may not be always put up step by step workflow for people to follow, but rather my thoughts on some issues.
(If you want any step by step stuff, regarding any techniques I've used or mentioned, you can contact me personally by leaving a comment, or by whatever means you can think of)
I have noticed I am having a trend in processing. Whenever I post anything to a US forum or mailing list, quite a number of people would compliment on the colour rendition of my images. Well, as I've stated in on of the processing workshops a few years before, one super important element in processing is to have a well trained or calibrated eye and mind. If you know what would look good, then definitely you are on your way. You just have to learn and practice the tricks and tools in your software and things will come in naturally. But as I see in most forums, people just don't know what makes an image look good.
Of course looking good is pretty subjective, but there are still a few key components that are generally accepted among amateur astronomers.
- low noise/grain, without cutting out fine details.
- small star size when shooting anything below 500mm (that is a signature for higher resolution)
- a large image scale (large number of pixels) -- this would usually violate with the low noise point, because resizing is usually the most convenient way of hiding the noise.
- good colour balance and contrast stretch
The first 3 points have a lot to do with image acquisition itself. It goes back to all those basics:
- having enough exposure: one good benchmark would be shooting at least for an hour with an F4 system -- you are guaranteed to have a decent image if you are shooting under a site with limiting 5.5 mag. (Although I had success shooting only 40min with F5.6... parental guidance needed for this kind of exposure)
- correct focus: Spend as long as you want to try to reach the best focus
- accurate tracking and guiding: this one is usually much less of a problem nowadays as the polar scopes are getting easier to use, and a longest 15min digital subframe would not need terribly accurate polar alignment
The last point on colour and contrast is the only part with nothing to do with the camera. On the contrary to public believes, I don't think it can really be taught. It is a matter of looking a a lot of pictures and decide which you would like, and then learn the methods to achieve that specific result. I can teach you step by step on all the things I've done to a certain image, but you won't be able to achieve the same result with another using the same tools and steps. The only way of doing it is through practice and training the eye.
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