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How to get rid of 'squares' in stretched image?

Russell Croman Astrophotography StarXTerminator Processing Deep Sky Artifacts
8 replies•629 views
Photon_Collector avatar
Photon_Collector avatar
Not sure what is happening here 

There are a bunch of purple blocks or squares that are visible all over the image. This happened once I ran StarXTerminator. Anyone know what this is or how to get rid of it?

Thank you!!

jaydeepappas avatar
jaydeepappas avatar
Did you calibrate with flats and dark flats/bias? 

if so, you mentioned you used starx. There is a “use large overlap” or similar checkbox for starx that specially states if starx leave blocky artifacts, to use that setting. It explains how it works and why in the tooltip if you hover over it. Give that a try.
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Photon_Collector avatar
Photon_Collector avatar
Did you calibrate with flats and dark flats/bias? 

if so, you mentioned you used starx. There is a “use large overlap” or similar checkbox for starx that specially states if starx leave blocky artifacts, to use that setting. It explains how it works and why in the tooltip if you hover over it. Give that a try.



Yes I used flats/darks/biases...but didn't realize there was that option...I will try that!
George Hatfield avatar
George Hatfield avatar
How about some details on how you processed the image?  I have not seen this problem.

George
EdFromNH avatar
EdFromNH avatar
As mentioned above, this is a known issue with StarX.  Possibly also with other tools that process images in tiles.  What other processes did you use?
Scott Horton avatar
Scott Horton avatar
Did you happen to run starx on a non linear image?
D. Jung avatar
D. Jung avatar
I noticed the effect is less pronounced if you enable the "use large tiles" setting in starX (takes 4 times longer).
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Danny Lee avatar
Danny Lee avatar
Hi Photon_Collector, 

I had a very similar issue when processing one of my recent images. The grid pattern appeared after using StarX. 

I've read that images with particularly dense starfields may be more prone to this. StarX breaks the image down into chunks when doing it's thing which I think is what you might be seeing here. 

The solution, at least in my case was to tick the 'large overlap' box in StarX before running star. It takes a bit longer to run but it did the trick. Here is a link to the issue I had: Checkerboard pattern after stacking and star removal? - AstroBin

CS 
Danny
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Don Roy avatar
Don Roy avatar
I can second the two links above. The software itself says the same.