Please stretch away!

[Rustang]

I was imaging Andromeda last night, I managed to get 4hrs worth of 5min subs. I was really excited to see the stack but was quickly disappointed! It didn't look much better than my very first attempt in regards to detail obtained etc and that was only around 1hours worth of 1min subs. So what does it take to do Andromeda justice? Also how do you get the colour's that Ive seen in other Andromeda images? as my stack is just that washed out light orangy brown colour!

Stacked in APP. SW80ED DS PRO, Canon 600D astro modified. 0.8x reducer, Optolong L-Pro light pollution filter.

Edited September 22, 2020 by Rustang

[vlaiv]

Processing of astro photos is a skill to be learned.

Maybe watch some of videos explaining the process. You can also post your image here (32bit fits/tiff is the best option) for other more experienced members to show you what image really contains (there is usually more to data than people starting out with processing are able to show).

[Rustang]

23 minutes ago, vlaiv said:

Processing of astro photos is a skill to be learned.

Maybe watch some of videos explaining the process. You can also post your image here (32bit fits/tiff is the best option) for other more experienced members to show you what image really contains (there is usually more to data than people starting out with processing are able to show).

Ok, I will get the stacked image up to hopefully see whats there, whats the best way to go about posting a 32 bit file!?

[vlaiv]

Just now, Rustang said:

Ok, I will get the stacked image up to hopefully see whats there, whats the best way to go about posting a 32 bit file!?

I just usually attach it here in thread, but for very large files, I've seen people use drop box or google drive or possibly we transfer or similar.

In "My profile" section, there is "My attachments" part - you can see how much space you've used up here on SGL. There is 50GB limit I think - which is plenty I suppose.

[rnobleeddy]

Funny thing is I did the same last night. I only got 2 hours but that didn't end up looking a lot better than my earlier attempts. I've resolved to have a better attempt at processing tonight!

[Rustang]

If anyone would like to stretch my stack that would be awesome 👍

NewflatsAndromStack-St.tiff

[Rustang]

1 hour ago, vlaiv said:

I just usually attach it here in thread, but for very large files, I've seen people use drop box or google drive or possibly we transfer or similar.

In "My profile" section, there is "My attachments" part - you can see how much space you've used up here on SGL. There is 50GB limit I think - which is plenty I suppose.

Stack attached 👍

[gaz81]

I recommend this guy for processing guides

https://www.youtube.com/c/AstroBackyard

[vlaiv]

18 minutes ago, Rustang said:

Stack attached 👍

Usually that would mean linear data without any manipulation, but let's work with what we have:

There you go, yellow cast removed and colors closer to what you would find in a galaxy of that type.

This should really be done while the data is still linear - color calibration / balancing and gradient removal, but it can be done.

[Rustang]

4 minutes ago, gaz81 said:

I recommend this guy for processing guides

https://www.youtube.com/c/AstroBackyard

Currently going through his Andromeda processing video 👍

[Rustang]

5 minutes ago, vlaiv said:

Usually that would mean linear data without any manipulation, but let's work with what we have:

There you go, yellow cast removed and colors closer to what you would find in a galaxy of that type.

This should really be done while the data is still linear - color calibration / balancing and gradient removal, but it can be done.

What do you mean by linear data, this is straight out of Astro pixel processor, i havent done anything to it!?

[vlaiv]

7 minutes ago, Rustang said:

What do you mean by linear data, this is straight out of Astro pixel processor, i havent done anything to it!?

This data looks like it had curves applied to it - which means it is not linear.

This is what linear data for M31 should look like (roughly):

core is much brighter than anything else and there is only a hint of other structures in the image.

Here is for example single luminance sub from my M31 a few years back:

Histogram of such image is much narrower:

Something has been done to your image that is non linear transform and once you do non linear transform, you loose ability to easily fix color balance or remove gradients (algorithms for that assume data linearity).

[Rustang]

There's something set in Astro pixel processor i didnt know about then, any ideas where that could be in the settings!?

Edit, just found it- stretch was ticked so ive un-ticked it and will try and upload the new file!

 

Edited September 22, 2020 by Rustang

[vlaiv]

Just now, Rustang said:

There's something set in Astro pixel processor i didnt know about then, any ideas where that could be in the settings!?

 

I don't use APP so I can't tell. I think that @ollypenrice uses it quite a bit. Olly could you shed some light on this?

Maybe it is Gamma setting or something like that?

[Rustang]

2 minutes ago, vlaiv said:

I don't use APP so I can't tell. I think that @ollypenrice uses it quite a bit. Olly could you shed some light on this?

Maybe it is Gamma setting or something like that?

Stretch was ticked lol, i didnt see that the box was ticked when saving! 😄

Edited September 22, 2020 by Rustang

[Rustang]

Nostretchtest.tiff

Edited September 22, 2020 by Rustang

[Rustang]

New file above!

[ollypenrice]

25 minutes ago, vlaiv said:

I don't use APP so I can't tell. I think that @ollypenrice uses it quite a bit. Olly could you shed some light on this?

Maybe it is Gamma setting or something like that?

No, I don't have it Vlaiv.  I constructed a big mosaic recently using panels captured and pre-processed in APP by Yves Van den Broek and I also used his APP-generated mosaic as a template, but I post-processed exclusively in PI, Registar and Photoshop.

The first thing I'd say is that many M31s (including my own) are probably too colourful with the arms too blue and the core too red.

Personally I don't like to use any automated stretches, including DPP. The stretch is the defining operation in post processing and I like to do it slowly, in small increments, and by hand. Once I get the background up to a reasonable brightness I stretch only above that.

Olly

[Stuf1978]

I also had a shot at M31 last night but haven't had a chance to look at the data yet. I can tell you that every time I've tried it in the past I've given up as I find it a really difficult target to process and my images just look terrible 😂

[Rustang]

13 minutes ago, Stuf1978 said:

I also had a shot at M31 last night but haven't had a chance to look at the data yet. I can tell you that every time I've tried it in the past I've given up as I find it a really difficult target to process and my images just look terrible 😂

Ive been on it all day and got no where!! lol

[Stuf1978]

29 minutes ago, Rustang said:

Ive been on it all day and got no where!! lol

Lol, fingers crossed you get something out of it 😃

[Rustang]

Right, I'm leaving it there, Ive been going round in circles all day! Its not crap and its not fantastic but its ended up being better than my first attempt last year, the colours may still be a little out but I like it the way it is!

I think I may stick with the Neb's! 😊

 

 

 

Edited September 22, 2020 by Rustang

[vlaiv]

Oh, I had a blast processing this data ...

This is not how I would normally process the data, but I wanted to recreate as much as possible that "popular" look that most people go for - boosted saturation, too much blue and dark red and so on ...

[Rustang]

22 minutes ago, vlaiv said:

Oh, I had a blast processing this data ...

This is not how I would normally process the data, but I wanted to recreate as much as possible that "popular" look that most people go for - boosted saturation, too much blue and dark red and so on ...

Nicely stretched 👍 Its hard to stay away from boosting colours etc, especially after shooting nebs. Hopefully I haven't gone to over processed, it was a bloody fight to get any colour!. How did you find the data? Did you play around with the original stack or the second one? 

Edited September 22, 2020 by Rustang

[vlaiv]

8 minutes ago, Rustang said:

Nicely stretched 👍 Its hard to stay away from boosting colours etc, especially after shooting nebs. Hopefully I haven't gone to over processed, it was a bloody fight to get any colour!. How did you find the data? Did you play around with the original stack or the second one? 

Above image was from linear stack. There are some residual issues, either from flats or something else - see that darker line at the top, even after crop.

After binning the data, it was rather smooth and ok to work with, I did not do much noise reduction at all.

Here is what I did:

1. Loaded posted file, cropped away artifacts and separated channels

2. Loaded those separate channels to ImageJ - there I binned data x3 and removed background and background gradient

3. I found B-V 0.42 star and did photometric measurement on it - for color balance

4. Created artificial luminance after color balance (L = 0.2126*R + 0.7152*G + 0.0722*B)

5. I stretched luminance in gimp - levels, curves and a bit of noise reduction

6. I loaded RGB data in Gimp and did color compose to get back color image

7. I pasted stretched luminance over RGB image (which was not stretched) and set layer mode to Luminance

8. I then did temperature correction to remove yellow cast imparted by atmosphere

9. Boosted saturation

10. Desaturated yellow as core was really yellowish/orange

11. Saved as 8bit data ...