Can masked stretch be done in ST?

General discussion about StarTools.
opestovsky
Posts: 14
Joined: Fri Oct 22, 2021 6:19 pm

Re: Can masked stretch be done in ST?

Post by opestovsky »

BainthaBrakk wrote: Mon Nov 01, 2021 11:44 am
opestovsky wrote: Mon Nov 01, 2021 9:10 am
BainthaBrakk wrote: Sat Oct 30, 2021 11:28 am I processed(a bit fast maybe :) ) the only data I had on the subject to try to help with the problem OP had.
Thanks.
How fast was "fast"?

If it isn't too long, could you do my data, in the first post?
Hi!

I am sorry, I am less than useless at processing HOO-palettes from OSC-data. :D What I was suggesting was that you remove the stars from your "quick and dirty"-version with Starnet++ and then adding stars back from processing the stars separately. That is a bit hard for me to help with as I don't have the cropped dimensions.

Regards -

/Ulf
I've never been able to successfully remove stars from ST-processed images. Something in autodev and/or filmdev and/or wipe and/or color modules breaks them for Starnet++. The results come out looking really poor, with tons of artifacts.
BainthaBrakk
Posts: 11
Joined: Wed Sep 16, 2020 7:45 pm

Re: Can masked stretch be done in ST?

Post by BainthaBrakk »

I've never been able to successfully remove stars from ST-processed images. Something in autodev and/or filmdev and/or wipe and/or color modules breaks them for Starnet++. The results come out looking really poor, with tons of artifacts.
Hi,

It absolutely leaves artifacts sometimes, mostly with really big stars. This is not Startools related though so could you message me instead about this?

Regards -

/Ulf
opestovsky
Posts: 14
Joined: Fri Oct 22, 2021 6:19 pm

Re: Can masked stretch be done in ST?

Post by opestovsky »

BainthaBrakk wrote: Mon Nov 01, 2021 5:54 pm
I've never been able to successfully remove stars from ST-processed images. Something in autodev and/or filmdev and/or wipe and/or color modules breaks them for Starnet++. The results come out looking really poor, with tons of artifacts.
Hi,

It absolutely leaves artifacts sometimes, mostly with really big stars. This is not Startools related though so could you message me instead about this?

Regards -

/Ulf
If it isn't ST related, then we aren't talking about the same thing.
I'm taking about large artifacts, quarter of the size and brightness of the stars themselves.
When I do photometric color calibration and stretch in Siril on the same datasets, zero such artifacts appear.
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Re: Can masked stretch be done in ST?

Post by admin »

BainthaBrakk wrote: Mon Nov 01, 2021 12:08 pm Ivo, I think this is a good example where you are trying to find evidence of tampering when there really is none.

The "6-spike" pattern is a result from pinched optics of my Esprit 100. These appear sometimes in triplets/quadruplet scopes when photographing in sub-zero temperatures. You might not be familiar with that phenomenon in Australia I guess. ;)
:D Indeed. No such troubles here
I'm glad I'm not going insane though and the odd diffraction pattern has an explanation.
I mostly use Autodev. When I get a problem, I try something else. Sometimes (mostly with mono data) it is really hard to get a result I find appealing when using it. That doesn't mean I think it is bad. It might be that I am doing something wrong, I have some stacked files you could have a look at that really shows this.
Always happy to have a look and see if I can make ST better.

With regards to star removal and artifacts (as well ST's Heal behaviour!), layering stars back in (if your really must got this route) should ideally be done with a Lighten operator (not an Add operator!). E.g, a pixel only gets layered back in if it is brighter than the pixel that it will be replacing.

An Add operator just adds the star to the underlying neurally hallucinated data (and any artefacts), causing the result to be a combination of artefact and original star. The Lighten operator avoids this.

For example, StarTools' Heal module can be made to explicitly exploit this, by forcing it to always place back pixels that are darker than the star it is removing. This way, a Lighten operator will always place back the star with all its pixels intact.
Ivo Jager
StarTools creator and astronomy enthusiast
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