Reworked Southern Cross

Atmos (Colin) · #1 31-05-2015, 05:16 PM

Been finding around a bit over the last two days. Bought PixInsight this afternoon and have come to the realisation that DeepSkyStacker does a better job with my Nikon RAW files (.NEF) than PI does. Not sure whether this is just my lack of skill (only been using PI for a few days). Although DSS kills colour saturation, appears to make a cleaner stack.

Anyway, this is 113x30' images with my Nikon D700 + 24-120mm F/4 at 112mm (kept falling back from 120mm).
Stacked in DSS and processed in PI. May have pushed the curves a little too far bit it isn't too bad for a 15 minute job. Still don't understand half of what I am doing, fumbling through and hoping for the best at the moment.

RickS (Rick) · #2 31-05-2015, 06:58 PM

There sure are a lot of stars in that field, Colin!

I've never done DSLR processing in PI but I'd be surprised if it doesn't do a great job once you figure out the right parameters. If you're using BatchPreprocessing to do the stacking make sure you do the final integration using ImageIntegration with a suitable rejection algorithm and tweak the rejection parameters for best SNR (the BPP defaults are unlikely to be optimal.)

Cheers,
Rick.

Atmos (Colin) · #3 31-05-2015, 07:20 PM

I am not sure why but when I ran it through PI it cast everything with a strong green overtone that I just couldn't figure out how to process out. Chances are I did something wrong! Was my first ever attempt at using PI so I did leave most things as defaults. The green overtone would have been left over from debayering. DSS natively did a much better job with the debayer process. Probably my own fault though, PI has been around long enough that it'll probably do things I cannot even imagine

RickS (Rick) · #4 31-05-2015, 07:46 PM

Colin,

If the problem is just a green cast then SCNR is your friend. It will remove green like magic!

Cheers,
Rick.

IanP · #5 31-05-2015, 08:01 PM

First of all, you have a lot of data …

Is it possible that you post somewhere better resolution image?
In PI there are some tools that allow you to eliminate/enhance certain things, for example, to remove some greenish stuff, as Rick said, you can use SCNR-Green.
The other thing to remember is that you have to do a lot stages using image-clone-based-mask.
And the last thing I’d like to stress here is that in processing DSLR images I’d first extract L (RGBspace=all1), process L separately, and then combine L with the RGB back again … but I guess you know that altogether …

Atmos (Colin) · #6 31-05-2015, 08:48 PM

I tried that, worked a little but only to some extent. In saying that, only bought PI some 8 hours ago so my experience with is it very limited thus far.

Quote:

Originally Posted by RickS

Colin,

If the problem is just a green cast then SCNR is your friend. It will remove green like magic!

Cheers,
Rick.

IanP:
I actually didn't separate them, I do remember when I watch my first YouTube tutorial on it a week or so ago, the PI team recommended that but I forgot all about it! Will have to do some more YouTubing, get a better understanding of why they suggest separating the L and all that.

https://dl.dropboxusercontent.com/u/27436364/SCIIS.jpg

A link to a higher res.

Rod771 (Rod) · #7 31-05-2015, 11:11 PM

Great shot, Colin! Nice field.

I often get strong colour casts after integrating calibrated raw subs in PI (mainly blue). First thing to do is create a small preview selection on an area of background, it doesn't have to be a large preview, a small selection will do. Next, open the Background neutralization tool and select the preview you have created as a reference. Click apply and the colour cast should be balanced.

The result could look ugly at first, just click the auto apply button on the STF (Screen transfer function) tool to reset the artificial stretch. Next thing to do is crop any nasty edges then use DBE to correct any background gradients.

Stick with integrating in PI, it is far more powerful than DSS.

Cheers

Rod

Atmos (Colin) · #8 31-05-2015, 11:29 PM

That's how I ended up with the following, it still has a noticeable green overcast. The back colour where it is supposed to be yellow has a green tonal cast. It was incredibly green before I did the Background Neutralisation, million times better but it's still present.

Hopefully this won't be an issue forever though, going to have a SBIG ST2000XM arriving in the next week or two thanks for the IIC Classifieds

I guess nothing beats a DSLR for super wide fields though.

Quote:

Originally Posted by Rod771

Great shot, Colin! Nice field.

I often get strong colour casts after integrating calibrated raw subs in PI (mainly blue). First thing to do is create a small preview selection on an area of background, it doesn't have to be a large preview, a small selection will do. Next, open the Background neutralization tool and select the preview you have created as a reference. Click apply and the colour cast should be balanced.

The result could look ugly at first, just click the auto apply button on the STF (Screen transfer function) tool to reset the artificial stretch. Next thing to do is crop any nasty edges then use DBE to correct any background gradients.

Stick with integrating in PI, it is far more powerful than DSS.

Cheers

Rod

Atmos (Colin) · #9 31-05-2015, 11:30 PM

Double post for image!