Wrestling with ngc1333 first lrgb image

[Allinthehead]

5 hours ago, AKB said:

 

@Allinthehead,

This is a super set of data to play with... thanks for posting. 

 

Thanks Akb. I find it a great help to practice on the data of others.

4 hours ago, simmo39 said:

 

I have been bitten by this target to, not an easy target to get right. After doing about 10 hours or so with my DLSR im still no where near your fantastic image.

 

Thanks Simmo. It's a stunning area of the night sky. I think the image above has 19 hrs at f6.3 and needs alot more.

[alan4908]

On 12/5/2016 at 21:16, Allinthehead said:

Hi all. This is as the title says my first effort at an lrgb image using the zwo asi1600. 

L=10 hrs of 180 second subs Gain 164

RGB=9 hrs combined of 180 second subs Gain 260

I used dss to stack the images which were taken over multiple nights(5 i think). I used the best rated luminance sub as a reference frame for stacking and aligning the rgb. Then processed in cs6 luminance separately. Combined the rgb channels, used gradient exterminator, stretched then pasted the luminance over the rgb as a layer and changed the mode to luminosity.

I've tried adjusting the saturation, brightness and contrast but this is the best i can get out of the data. For the time i put into it, i'm disappointed. Can anyone spot any errors in my workflow or suggest anything that might help.

Thanks for looking.

Richard. 

Hi Richard

Firstly, if this is your first effort at an LRGB image then it is very good !

Since you wanted some constructive remarks on how to improve, I decided to have an attempt at processing your data in Pixinsight (DBE, SCNR Green and Colour Calibration), CCDstack (Deconvolution, DDP on the Lum) and PS (everything else). I also put the FITS files through CCDInspector which I find very useful for quantifying image quality.  

CCDInspector told me was that your average star aspect ratio is 30 - which indicates something needs a tweat in your acquisition setup. I attempted to compensate for this in Photoshop by taking both the Lum and RGB layers and using the offset filter to move them relative to each other with the blending mode set to darken, this improves the shape of the stars. You also seem to have a slight flat errors in both the Lum and RGB data which I tried to eliminate in Pixinsight by setting the correction mode in DBE to division. 

On the Lum the workflow was DBE, decon, DDP stretch, noise reduction, sharpen (HPF and unsharp mask), noise reduction.

On the RGB: the workflow was DBE, SCNR Green, Colour Calibration, I then used levels to bright the image and blended with Lum using the Luminosity blending mode. To get colour into the faint parts I used shadows Highlights.

To get a bit more colour, I flattened the image into LRGB and went into LAB mode and boosted the contrast in both the a and b channels.  I then used PS noise reduction and Noel Carboni's tool for color blotch reduction.   

Hope this helps, the result is below !

Alan

 

 

 

 

 

 

 

[Allinthehead]

 

4 hours ago, alan4908 said:

Hope this helps, the result is below !

Hi Alan.

That was a very comprehensive reply. Thanks for taking the time. It's always a help to see the workflow of others. You are correct about the data. I'm not guiding yet so the 3 minute subs were pushing it a bit. You seem to have the same issue with the gradients that i had. There's a heavy blue cast in the image. You did a much better job with the noise reduction.

Thanks again.

[PatrickGilliland]

I think for the exposure length you have done a fine job.  You can process it to death but will always be data limited.  To get more i would focus on longer subs if viable and introduce those into the image.

My old version that i may revisit (far too much NR) had 68*900 (17 hours of longer subs) subs to really start to see the detail.

Paddy