Basic Photoshop tutorials for NB imaging

[Lee_P]

Can anyone recommend some simple Photoshop tutorials to help me with processing NB images? Importing the different images; layering them; colourising, etc. Step-by-step would be great, I'm very new to the wonderful world of narrowband...

Thanks!

[newbie alert]

I have this saved..cant remember if it's Photoshop or not

 

[Lee_P]

Thanks, I'm favouriting that one for sure. Only catch is that it stops short of explaining how to layer and combine different images.

[geordie85]

21 minutes ago, Lee_P said:

Thanks, I'm favouriting that one for sure. Only catch is that it stops short of explaining how to layer and combine different images.

What I do is stack my images in DSS using the same reference frame for all 3 bands, just leave the reference frame un-checked in the other 2 bands. That way all 3 bands will already be pretty much aligned.

I open Photoshop then open all 3 images (HA, O111 and S11). I then record an action that crops the edges ever so slightly so all 3 images will receive the same crop. I copy 1 of my images (ctrl A then ctrl C) then click file then open. Change it from grey scale to rgb colour then paste each image into the corresponding channel then process this image as normal. 

For colouring I use these 2 tutorials depending if I'm doing a bi-colour or full hubble pallette. 

http://www.starrywonders.com/bicolortechniquenew.html this one for bi-colour. 

http://bf-astro.com/hubblep.htm this one for hubble pallette 

I hope this helps.

Please note that if I'm doing bi-colour I won't combine and process, I'll process each channel separately but this is just how I do it. Others will differ. You just have to find what works for you.

[Lee_P]

On 9/3/2017 at 23:04, geordie85 said:

What I do is stack my images in DSS using the same reference frame for all 3 bands, just leave the reference frame un-checked in the other 2 bands. That way all 3 bands will already be pretty much aligned.

I open Photoshop then open all 3 images (HA, O111 and S11). I then record an action that crops the edges ever so slightly so all 3 images will receive the same crop. I copy 1 of my images (ctrl A then ctrl C) then click file then open. Change it from grey scale to rgb colour then paste each image into the corresponding channel then process this image as normal. 

For colouring I use these 2 tutorials depending if I'm doing a bi-colour or full hubble pallette. 

http://www.starrywonders.com/bicolortechniquenew.html this one for bi-colour. 

http://bf-astro.com/hubblep.htm this one for hubble pallette 

I hope this helps.

Please note that if I'm doing bi-colour I won't combine and process, I'll process each channel separately but this is just how I do it. Others will differ. You just have to find what works for you.

Ok, so I've finally got some data that I can use to try this out! geordie85, using your instructions I've got as far as the bf-astro tutorial. I've got a very green picture, like the tutorial's Image 1. I'm having trouble getting it to look like Image 2. Could anyone fill in the blanks and clarify the missing steps? Thanks!

[geordie85]

Unfortunately even though there are tutorials on how to/ what to do to get the best out of your images, it's not an exact science and adjustments need to be made for each image. 

You'll just have to play around with the sliders until you get an image that pleases you.

[Lee_P]

1 hour ago, geordie85 said:

Unfortunately even though there are tutorials on how to/ what to do to get the best out of your images, it's not an exact science and adjustments need to be made for each image. 

You'll just have to play around with the sliders until you get an image that pleases you.

For sure, but I was playing about with sliders for a long time but not getting anywhere near the desired result. I think I'm misunderstanding some basic steps. Specifically, if I understand the tutorial correctly, I'm aiming to get the histograms for the R G B channels to look approximately the same. My G channel (H-a) looks great, but R and B are both quite narrow. (Makes sense given the amount of data they contain). I try adjusting them in levels, but the actual histograms don't change.

Here's a screenshot of what I'm working with. I expect I'm missing something really basic that experienced imagers just instinctively understand!

 

 

 

[Art Gecko]

I've never done Nb imaging, but I'd say load up your 3 files separately and give the levels and curves a tweak in each until the histograms on each image looks about the same size and position... THEN load them into your final picture as RGB channels... that way it should be easier to balance the colours.

[Lee_P]

Ok, that sounds sensible.. But whatever I change, the actual histogram remains the same. So I can't get it to be more stretched out like the H-a naturally is, if that makes sense..? Is there some Photoshop checkbox to make the histogram update?

 

 

[Art Gecko]

Try stretching the curves rather than the levels of the other two to get them to expand the histogram spike to the same size as your Ha.

[Lee_P]

19 minutes ago, Art Gecko said:

Try stretching the curves rather than the levels of the other two to get them to expand the histogram spike to the same size as your Ha.

Thanks, this is what I needed to do!

[geordie85]

2 hours ago, Lee_P said:

For sure, but I was playing about with sliders for a long time but not getting anywhere near the desired result. I think I'm misunderstanding some basic steps. Specifically, if I understand the tutorial correctly, I'm aiming to get the histograms for the R G B channels to look approximately the same. My G channel (H-a) looks great, but R and B are both quite narrow. (Makes sense given the amount of data they contain). I try adjusting them in levels, but the actual histograms don't change.

Here's a screenshot of what I'm working with. I expect I'm missing something really basic that experienced imagers just instinctively understand!

 

 

 

My guess is because you have a layer mask you'll need to flatten your image first, then use the sliders. 

[Lee_P]

This is where I managed to get it to. Very shoddy, but at least some of the concepts are starting to make sense. I had to *really* stretch the SII and OIII to get their histograms even get close to the H-a. This introduced loads of noise. Is this normal? Should I be taking longer subs for SII and OIII to improve the SNR?

 

 

[geordie85]

More data will always be a plus. Have you considered not stretching your Ha data so much. You won't have to worry about stretching your o111 and s11 data so much either

[Lee_P]

Just now, geordie85 said:

More data will always be a plus. Have you considered not stretching your Ha data so much. You won't have to worry about stretching your o111 and s11 data so much either

That's a thought. I just made the H-a look as good as it could.

[geordie85]

39 minutes ago, Lee_P said:

That's a thought. I just made the H-a look as good as it could.

It's easy to fall victim to having one channel stronger than the rest which then dominates the final image. 

Sometimes less can be more.

[Uranium235]

On 03/09/2017 at 20:16, Lee_P said:

Can anyone recommend some simple Photoshop tutorials to help me with processing NB images? Importing the different images; layering them; colourising, etc. Step-by-step would be great, I'm very new to the wonderful world of narrowband...

Thanks!

If you want to combine images (ie: create a composite for a higher dynamic range) its fairly straightforward. The video I created (the first one), was just to cover the basics - so I didnt really want to go into more depth.

A decent little tutorial for composite images is here:

http://www.astropix.com/html/j_digit/laymask.html

After a while you will notice that layer masks can get you out of all sorts of trouble, and their uses arent just confined to restoring cores of blown-out nebulae or galaxies.

 

Edit: I think whatever video I do next, I should hardcode the annotations in with the video rather than reyling on post production youtube annotations becuase they seem to lose sync.