This is how I remove light pollution from my images. It is not perfect, but gives a good starting point. In DSS I always embed changes and never apply and save the tiff file with zip compression. Zip is lossless compression.
The first thing I do with Iris is set the working path. Press Ctrl R (File | Settings) and adjust the working path. I have a directory e:\camera where I store all my images in directories, so I have set that as the working path. This will then make Iris to save and load files from that directory (folder). This will now be saved when you exit Iris (I think).
The next thing I do is load the tiff file as saved by DSS and on the Threshold toolbar, I press Auto.
In the menu, I click on Processing and scroll down near the end to "Remove gradient (polynomial fit)". Both radio buttons are set to Medium and I also enable "Balance background colour", then click OK. When the image is filled with + signs, then on the Threshold toolbar, choose Auto.
To save the image, click on the icon which has two sets of >= to the right of the H icon. Click on the command window so the > is not highlighted.
Type in:
savebmp imagename
where imagename is the name you want to give the image. This is useful for further processing with Photoshop or Gimp.
savejpg imagename 1
will save as a high quality jpeg image with 1 indicating the highest quality.
The files will be saved into the working path we set at the beginning.
I hope this simple tutorial is helpful for someone.
Naddie
