By Phil Schumacher
www.cloudtrap.com
Introduction
An amateur astronomer for 5 year
2 ½ years of taking black & white astronomical Images
Mainly deep sky images (nebulas, galaxies and star clusters)
Why the need for image processing?
Raw
and Processed image of M42
Types of
processing:
•Corrections – Scientifically Valid
•Enhancements – Not scientifically Valid
•Retouching
Telescope
and camera setup
Three F’s (Finding, Focusing, Following) (Trailing)
Imaging Software (MaxIm/DL
CCD)
1.
Calibration (Remove camera and telescope artifacts)
2.
Align &
Stack (Increase
signal to noise ratio)
3.
Stretch (Make desired part of image visible)
4.
Enhance (Improve
presentation)
Why stack images?
Obtain longer effective exposure to
improve signal to noise ratio.
Better Tracking
Less likelihood of a ruined shot
•Wind
•Light struck
•Bump
Light pollution
Keep bright areas under control
•Somewhat higher noise
•More memory
•Need to align and stack in software
Corrections:
The Electron Well
Dark Subtract and Flat frame correct
Whirlpool Galaxy Example
Making
Flats (Setup)
Advanced
calibration with scalable dark frames using bias
frames
Processing
Example M42
Debloom
if necessary
Align & Stack images
Screen Stretch
Noise adds by the square root of the sum of squares.
The noise of the signal is the square root of the signal.
Non-linear
Stretch (DDP, Log, Gamma, Histograms)
Sharpening
(Filter, Unsharp Mask, Deconvolution)
Mosaic
building
Star fixing with clone tool
Pixel editing
***Last***
Extra topics:
Auto-guiding
Methods of finding Objects
Telescope types and trade-offs for photography
Photometry concept (Light curves of stars)
Astrometry concept (Orbits of Comets and Asteroids)
Color imaging concepts
Consumer Digital cameras
Planetary imaging