Determining ROI in StarTools

[Larry 1969]

Good day all!
I use a fairly typical workflow in StarTools and I'm wondering how to determine the ROI in the second AutoDev?
Different regions produce different results. Some appear too dim while others seem blown out...
What process do you use?

Thanks!

Larry

[startoolsastro]

Hi Larry,

You may find this part of the documentation helpful.
For example, this image in the documentation shows what the RoI does;

(Confining the Region of Interest ("RoI") progressively to the core of this galaxy, the stretch becomes more and more optimised for the core and less and less for the outer regions.)

Any trouble/questions, do let me know!

[Juno16]

Thanks for the question Larry. Ivo, if you can offer a suggestion, I would highly appreciate!

I usually select a “slice” of the brighter portion of the dso as my roi. I read in the documentation that a properly selected roi will reduce the star bloat or “halos” from oversaturation. I have found that a manual dev works better for me than autodev to control star halos. I am obviously using the roi incorrectly! I am also probably loosing some dimmer portions of the dso by using a manual develop.
Star halos or bloat is constantly an issue for me whether I am using using the dslr or ASI 533. I use a low iso/gain and don’t get carried away with exposure times. I keep the histogram about 1/4 from the left with the dslr and just barely on the right side of the left border with the ASI533.
This occurs even when using a dual narrowband filter (Optolong L-enhance).

Should I reduce the size of my roi to control bright star bloating better? Any suggestions?

I really enjoy using Startools and appreciate your constant improvements and support!

Thanks you!

[Larry 1969]

Thanks for that Ivo!
So, out of the images above, I would think the top right would be most correct right?
I never thought of using the entire galaxy as my ROI... I had been using a slice of the outer arms.
Since I'm at 840mm focal length, I tend to not capture entire objects like the Elephant's trunk for example.
In that case should I select the trunk itself with a portion of the surrounding nebula?

Thanks again!

Larry

[startoolsastro]

star bloating

AutoDev should always produce better controlled stars than Develop. Of course, any further optical characteristics (diffraction patterns or - less desirable - secondary reflections) are also made visible by AutoDev. To better diagnose any problems, would you be able to post an image showing a comparison between AutoDev and Develop where you feel Develop is doing "better"? Thank you!

I really enjoy using Startools and appreciate your constant improvements and support!

And ST wouldn't be what it is without engaged users like yourselves!
I just purchased an RX 570 by the way for testing purposes (I'm getting quite the collection of GPUs! ), so I can better preempt and fix any bugs related to these cards.

So, out of the images above, I would think the top right would be most correct right?

Of course, it's all about personal preference, but indeed the top right image would be closest to what I would go for myself as well!

I never thought of using the entire galaxy as my ROI... I had been using a slice of the outer arms.

If you feel that this is a good example of the type of dynamic range problem that AutoDev should optimize for, then that can of course be valid. Trouble is, you may possibly be missing out on the fainter parts of the disc.
The RoI essentially says this to AutoDev;
"Hey AutoDev, see this? This is what I want you to pretend is all you can see. Now create a stretch for me that shows as much as possible in that area, but apply the stretch to the whole image. Go."

In that case should I select the trunk itself with a portion of the surrounding nebula?

Select the area for which you want to show as much detail as possible. Leave out the area that is not interesting to you.
Be mindful that AutoDev's job is to find the optimal global stretch. To bring out further detail locally, use other tools (HDR, Contrast, Sharp) to refine your image.

[Juno16]

I just purchased an RX 570 by the way for testing purposes (I'm getting quite the collection of GPUs! ), so I can better preempt and fix any bugs related to these cards.

Now, that’s support and service!

Me and my RX-570 are set!

Thanks

[Larry 1969]

Ivo,

Your customer support is top notch and I continue to recommend StarTools to astrophotographers in my various Facebook groups!

Larry

[bobharmony]

Larry - my answer is a clear "it depends"

Different regions produce different results

I experiment with the ROI when working on any target. I almost always want to include the core, but sometimes there are outlying regions that I don't want to lose (as in my recent M33 image) and I will extend the ROI to some of them. The Iris comes to mind as a target that benefits from an extended ROI as well. I am a convert and almost never use the manual develop module anymore.

Bob

[starfield]

The other thing I do is to play with the Ignore Fine detail. Helps tap down noise.