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Basic CCD Image Processing Questions

Started by tschonis, 02/27/2005 07:48PM
Posted 02/27/2005 07:48PM Opening Post
Hello. I am a an avid film astrophotographer, so I have a few questions about CCD image processing. I am a sophomore Physics and Astronomy major at the University of Nebraska, and I work for one of our department research teams gathering data for the photometry of Active Galactic Nuclei using our 16" Meade LX200 and an SBIG ST-7 camera. The data we need for our research only is concerned with the raw data, so we dont do much image processing. However, with my interest in amatuer astronomy and astrophotography, naturally I would like to process our images to make them look pretty and such (I also have theopportunity to use the telescope to image obhects of interest to me). I dont have time to image with the color filter wheel, so I am concerned here only with processing B&W images. Attatched is a 10 minute exposure of one of my favorite objects we study, NGC 4051. This image is raw. I would like to know what steps I need to take in order to clean this image up and make it look decent. I know I need to have sky flats and darks, which I have access to, but how do I utilize this. Since I am unfamiliar with CCD image processing, I have no clue how to do this. I have access to CCDOPS, CCDSoft, and Adobe Photoshop on my own computer. Also, I plan on stacking more images than just this one. Do I need to process each individual image before stacking, or can I stack raws and process the result? Anyhow, I guess all I am asking of the experienced CCD imagers here, is what are the basic steps you take to process a monochromatic image. Sorry, but this image has some stuff superimposed on it such as an identifiable marker for the galaxy and the magnitudes of reference stars. But anyhow, this is an example of one of our raw images. Thanks alot, I greatly apprciate it.

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tschonis's attachment for post 22542
Posted 02/27/2005 08:37PM #1
Taylor, I don't use CCDOPS or CCDSOFT to process but CCDSOFT would be my choice then Photoshop. They will do what you need. To start you want to subtract the dark frame and divide the flat frame from each RAW image then align and combine in CCDSOFT. These selections are under "Image". Then save as .tiff or .fits if you have the plugin for Photoshop. Open in Photoshop and adjust the Curves and Levels until it looks right. You can sharpen (I prefer unsharp mask over sharpen) blur if needed and remove artifacts with the Clone Stamp or Healing Brush Tools if needed.

This is very basic but it should get you started and we can offer more details if you want.

Cal