Thursday, February 14, 2013

The Orion Nebula--Photoshop Reprocessing Technique

This is a reprocessed image of the Orion Nebula I took last year.  I only managed to stack a few exposures due to both the weather and my inexperience in using a DSLR with a scope.  In the interim, I downloaded the free copy of an early version of Photoshop that Adobe kindly made available to everyone.  The reprocessed result is much better than the original and shows what can be achieved with a decent image processing package.  The weather has been particularly uncooperative this year and it has not been possible for me to take any images this year.  I hope things improve over the next couple of weeks.

I adjusted the histogram for the best black background and then boosted color information and did some smart sharpening.  The result was the blurring of the trapezium stars and a slightly hazier image, but I was able to pull out a lot more detail from the outer edges of the nebula. I also followed a Photoshop technique for shrinking bloated stars.  Here it is:

“Shrinking Stars” trick (from Jack attributed to Dan Verschatse):

1.                  Open the image file
2.                  Select > Color Range
3.                  Choose a bright bloated star
4.                  Exit Color Range
5.                  Select Modify Expand
6.                  Choose a reasonable expansion to include halos (say 8 to 10 pixels)
7.                  Set Feather to about 3 pixels plus or minus 1 pixel
8.                  Filter > Other > Minimize > radius (1 pixel) > OK

The original image as simply captured and stacked is below: