Friday, October 28, 2011

About image post-processing

Processing photos is touchy subject. Yes, you want to show off how amazing the sky is, but as you do things people really start to wonder what is "real." Are the colors real? What do you really see when you look? Do you want to highlight things to make it better than you would because you have a good idea of what it would look like without the atmosphere in between?

Here's my philosophy, so before I go in to how you can understand the why:
  • Show what is real
  • Don't process more than you have to
  • Get rid of artifacts of photography, pollution, and conditions where it doesn't add anything
  • Don't edit the color, even though that's generally not what you see through the scope.
The last bullet: your eyes aren't sensitive to color in dim conditions (the whole cones/rods thing, google it). So generally what you see when you look through a scope appears very desaturated. What you get back through the camera (because it doesn't have this affliction) does have color data. Blues, oranges, reds, and more seem much more prominent on the screen after the fact than they did through the lens when out in the field. This has less to do with the camera and the processing and more way your eyes are built.

That said, your eyes are better at seeing light and dark than not, so I'm ok with cheating a little bit to give a better representation...

My tool of choice is Deep Sky Stacker, a freeware astro tool just for this purpose. What it does is to take the data from multiple photographs garner detail and quality that no single frame captured. This also allows a certain amount of flexibility the final output as well, meaning you can push an image to be more dramatic or more realistic.
Let me start by saying the image from the previous post is similar to what you would expect to see through a 12" telescope, but with bolder colors and a bit less definition.

But, of course I think disclosure is disclosure; here is a completely unprocessed image from the set, exactly as it came off of the camera:

Not exactly magic; good source images still make all the difference.

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