Starting in astronomy
beginner’s guide to stargazing
By Mike Barrett
Photographing the planets (part 2)
Following on from last issue where we looked at the
equipment and capture of video to produce a photograph of the planets this issue looks at the processing of
the video into an image. This article really only scratches
the surface of image processing as there are so many
variables and methodologies that can be used. Having
mastered the basics will allow you to experiment and discover the best processing workflow for your requirements.
Assuming that you have captured some video. When
you look at it you will find that although it looks reasonable it will be quite wobbly and the focus will fade
in and out. What is required is to examine the video
and remove all the bad frames, grade the remaining frames, then process the good frames. This may
sound complex, and indeed it is, but there are software packages available to handle this processing.
If you think about what a video is you will discover
that it is just a series of static images that are played
together to form a smooth moving film. Just like the old
cartoon flip books you flick through the pages and the
image appears to move. We want to do the same, but
in our case the image does not move very much.
There are a number of different ways to create video
files, and a number of different formats. For the purposes
of Planetary Imaging we need to use the AVI format. This
creates a large file of individual frames. Other formats
such as MP4 have reference frames followed by information on what has changed since the reference frame,
this saves a lot of space but is not useful for our purposes
we need a format that saves entire individual frames.
The processing software that will be used is Registax,
though other applications are available Registax is the
most popular. Registax is FREE and if it was not provided
with your planetary camera it can be downloaded from
the Internet at http://www.astronomie.be/registax/. At
the time of writing the latest version available is Registax 6.1.0.8 which is the version used in this article.
The Registrax version 6.1.0.8 interface screen. Credit: Mike Barrett (All images)
When you start Registax you will see a blank
canvas with some menus, tabs, and configuration controls as shown in image 1. The three tabs
control the workflow of the application in the three
main areas of selection of alignment parameters,
aligning, and limiting and stacking the image.
First you need to load in a file. Press select and navigate to your captured files. Selecting one and loading
it fills the canvas with the first frame of the file. Using the
bottom control you can navigate through the video until you find a good frame to select the alignment points
More astronomy lessons
January 2013 (Issue #1)
Bringing the world of astronomy to the average person
has been something we’ve set our sights on every since
the first issue of the magazine, released in January 2013.
For those who haven’t been reading the magazine
since Day One, we’d like to invite you to peruse the
back issues. Our series of astronomy lessons to date
have covered topics such as identifying the constellations, buying your first telescope, the beauty of the
Earth’s auroras, a must-see list of celestial objects,
unpredictable nature of comets, a guide to getting started in astrophotography, and much more.
Catch up today online, download the issue as a
PDF, or purchase a printed copy from Blurb.com.
http://wp.me/p2Wsra-4g
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Astronomy: Guide to stargazing for students
April 2013 (Issue #2)
Buying your first telescope
http://wp.me/p2Wsra-cC
Orion the hunter
http://wp.me/p2Wsra-cy
October 2013 (Issue #3)
Recognising the night sky
http://wp.me/p2Wsra-iI
Cygnus the swan
http://wp.me/p2Wsra-iG
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