During optimization the program searches for the "best fit" in a box with a dimension set
by the search area control. At every optimization run (through all the frames) the program
searches the best possible shift for every frame versus the reference frame you selected. Every
run starts with the latest optimal shift. When you choose a small search path the program will
process faster but the optimizer might miss the perfect alignment position. On the other hand
if you search a real large area for every optimization run, it will increase the amount of time
it takes to for each processing run. A search radius of 5-10 pixels is usually sufficient.
Lastly you can set the lowest image quality (relatively to the best image) that you want to be
optimized (and later on stacked !!). Setting this to 0 will optimize all images, setting it to
100 will only optimize the single best frame (not recommended), a setting about 75% often
is useful. Be aware that when processing a set of FITS files it will be wise to include them all,
set the lowest quality to a low value to arrange this!!
9. Fast optimize
– during optimization this control will only optimize images that still need
(according to the settings) optimization. This feature is on by default.
10. Manual alignment
– When this is set you are asked to point at the alignment feature
in every image by hand. The alignment only starts after pushing the Align button or the
Align & Stack button. When you uncheck this checkbox after aligning several images by
hand the program will run on with automatic alignment.
11. Bias Subtract
– When you are aligning images sometimes static noise influences
the alignment. This static noise usually has a pattern (for example lines). This feature
subtracts a value from every pixel in the image during alignment. If the "real" value
of a pixel in a frame after subtraction becomes smaller than zero its considered equal
to zero. In a sense the whole picture gets dimmed slightly. It's rather effective and should
be used only if excessive static noise is seen in the background. Static noise is more
common when operating your camera at lower frame rates.
12. Optimize
– This button is disabled at startup and can be used after aligning the
images when auto-optimize is not set. The button optimizes all images in the sequence
only once. You need to have the "show graph" option on to see if this has any effect
on the registered images.
13. Align
– This button will start the alignment process. If auto-optimize is on then the
optimization will also be started. When aligning is completed, the program will take
you to the stacking page.
14. Align & Stack
– This is the “sit back and watch” command. This button will start
a fully automated process to first align the images then optimize them (if auto-optimize
is on). After that phase it will move to the stacking page and stack the images that
were optimized based on the settings in the optimizing options. After stacking, the
program will advance to the processing page. The routine is optimized for users that
like fast processing!
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Summary of Contents for NexImage
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