Quick Tip #1: [Pixinsight] – Unlinked stretch

There are so many things I’ve learned or picked up along my journey into astrophotography. Many of these things I’ve learned the hard way but also a lot have been through the help of others.

In order to pay some of this forward, I am starting a series on some tips & tricks I have picked up along the way that I thought might help others

The first topic is this:

If you’ve used PixInight, you know what I mean. You go through the entire process of stacking (either manually or in WBPP), then anxiously open the master light expecting to see … well, something. And you get something like the above.

What the heck is going on ? This effect comes from the bayer pattern common to our DSLR’s and OSC (One Shot Color) cameras. Since the most common bayer pattern has 2 Green to 1 Blue and 1 Red, our images come out … well, green.

If you (like me) are used to stacking in something like Deep Sky Stacker, you may get a more natural image as an end result.

Why is that ? By default, DSS will balance the histogram to Green, Red and Blue contribute approximately equally to the final histogram.

PixinSight can do this too but (surprise), it’s not the default. If you simply click the STF auto stretch icon in the toolbar

Then it’s likely you will see something like the above (maybe green, maybe red but probably NOT what you were probably hoping for)

The solution is simple, simply go to “Processes | All Processes | Screen Transfer Function” and you see something like this

Pressing the STF icon is like pressing the “nuclear” icon here

If we want to get a more natural look, all we need to do is select the image, then click the “Link/Unlink” icon

Then press “Nuclear” and … presto

A much more natural image to work with. Hopefully this helps you, and if you have any other questions, comments or corrections, please leave them in the comments and I will try to address them as best as I can.

Clear Skies

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