StarTools

Hello,

I'm sure this is user error, but wipe does not rid gradients nor does basic wipe remove gradients but they only make the situation worse, so I end up doing a lot of guess work to remove gradients or just moving to another program. This is just a simple 50% gradient from right to left where right side is 50% brighter than the left side on a linear RGB composite image. I've looked around at some tutorials and read the manual so I have an idea of the process but no matter what, the results are unsatisfactory so my methods are clearly incorrect. Any advice would be appreciated! thanks!

I've included some pics of the initial file and just some basic operations [which do not necessarily reflect every way that I've manipulated images to get rid of gradients]

Hi,

Looking at the inital file screenshot, the gradient is *very* extreme (e.g. an atypical dataset) and default setting will require more tweaking.
While Wipe should be able to remove the gradient by increasing the Aggressiveness parameter, it is probably a good idea to find out why the gradient is so extreme. Is this the result of some very extreme localized light pollution, or could this be the result of an issue with your flats?

Would you be able to upload the stack and share the link (Dropbox, Google Drive, OneDrive, WeShare, etc.), as well as share some acquisition details?

Thank you,

Hi Jack,

In addition to Ivo's suggestions (a link to download the stack would get us to the bottom of the issues right quick), I noticed a few other things...

You mentioned this as an RGB composite (and indeed there's a filename of new composite), but your Wipe screens seem to be locking you out of switching to the Color rendition.

Edge behavior doesn't strike me as an issue just yet. More something to tinker with last in Wipe, at least that's how I usually look at it.

Aggressiveness may need to be raised significantly. With my LP gradients, for LRGB or OSC a % of 90 or more, even 95, is not uncommon for me. Same for a few others here as well I think.

You said that Wipe is making things worse, and I'm going to take a wild guess at why. Wipe will show you areas of problems in the data and also back off from wiping anomalies, in case it might be real detail or dynamic range. If "kept" at that point, yeah it'd be a mess. There are two big bright blob areas towards the right side, at the top and the bottom, that look to me like this could be happening. Some artifact from stacking, dust spots, not enough cropping, all sorts of possibilities I suppose. But your Dark Anomaly Filter is off. You might want to try stepping that up to see what happens.

In the Color side of Wipe this is usually much more obvious. Here in the luminance it's a bit harder to perhaps see. Anyway it's something to try. If the anomaly filter isn't enough a Wipe mask can sometimes be used instead, if you can in fact find the defects that could be causing this.

Hi Jack,
apart from Ivo's and Mike's advice (increasing Aggressiveness) You could try the following:
- Increase precision to 128 x 128 px
- Dial in some Gradient falloff (10-30%) and increase
- Set Dark Anomaly Filter to at least 3-5 px
- Play around with the gradient edge behaviour options
Clearly the best option is to avoid such gradient undulation during capturing. (use lens hood against Moon, Streetlights etc.) and avoid reflection inside the OTA)

Cheers,
Jochen

Thanks for all the input I really appreciate it! I need to back track and revisit my stacking. I haven't done that yet and I didn't realize that I could not select the color rendition so I have probably made a mistake outside of StarTools. Sorry about that I feel a bit embarrassed about it. I will take your advice and make sure I haven't made a mistake elsewhere and try the suggestions all of you gave. Thank you so much.

Jack wrote: ↑Wed Dec 14, 2022 6:15 pm Thanks for all the input I really appreciate it! I need to back track and revisit my stacking. I haven't done that yet and I didn't realize that I could not select the color rendition so I have probably made a mistake outside of StarTools. Sorry about that I feel a bit embarrassed about it. I will take your advice and make sure I haven't made a mistake elsewhere and try the suggestions all of you gave. Thank you so much.

It's a steep learning curve - please don't ever feel embarrassed about being stumped and asking for a second, third, fourth pair of eyes. We've all been there at some stage.

Do let us know how you get on!

Clear skies,

Jack wrote: ↑Wed Dec 14, 2022 6:15 pm Thanks for all the input I really appreciate it! I need to back track and revisit my stacking. I haven't done that yet and I didn't realize that I could not select the color rendition so I have probably made a mistake outside of StarTools. Sorry about that I feel a bit embarrassed about it. I will take your advice and make sure I haven't made a mistake elsewhere and try the suggestions all of you gave. Thank you so much.

Hi Jack. For sure don't be embarrassed! In fact, give us as many background details as you can. Consult the Startools log even, if needed, for any questions as to steps you took in ST.

Was your data perhaps RGB filters via a mono astrocam?

I'm not yet convinced that anything is necessarily amiss with your stacking, so I don't want you to go chasing after ghosts here.

Let's talk about what you may have done to load your data into ST. Is it possible that, in Compose, you saw the Luminance, Color selector (top left option box) and perhaps chose "L+Synthetic L from RGB, Mono"

Not saying you did, but that would seem to match a few clues I see in your posted screenshots -- The fact that Wipe isn't allowing you to toggle to color; and that you have a NewComposite, and are still in tracking (Track/NR is green), but Compose is gray instead of green, and Entropy is shaded out.

If you did, that makes perfect sense, and is just a matter of learning a little "ST lingo." Trust me, it takes a little getting used to in order to understand how to read that particular set of Compose options.

Again if so, try again but keep the default option of L+Synth L from RGB, RGB. Think of the comma as a separator, and you have LUMINANCE OPTIONS, COLOR OPTIONS. And color options can of course include the complete lack thereof.