Processing IC1805 & IC1848 can it be improved?

[JLP]

Hi I am fairly new to astrophotography and have been using Startools for less than a year. What an amazing product it is squeezing out all those galactic pixels into amazing images. I have also found this forum helpful and informative. My humble equipment fits Ivo’s ethos of providing a low cost product for those folk imaging in an urban environment.
I use a Star Adventurer unguided with an Olympus OMD EM5MKII camera tethered to a laptop and pro lenses 40-150mm f2.8 and 300mm f4. I have just brought an IDAS-LPS-D1-77 light suppression filter. I am imaging from my back urban garden 25miles east of London in a yellow banded area. I have had some success with galaxies but really wanted to have a go at nebula, that’s why I got the filter.
On the night of the 7th Nov I had a go at a wide field shot of The Heart & Soul Nebula (IC1805 IC 1848) there was a bit of a moon out early on but I captured 162, 60sec (2.7 hours), 150mm, ISO 800 f2.8 (53.6mm aperture), 29 Dark frames, 48 Flat frames, 49 Dark Flat frames and 50 Bias frames all RAW of course. These were stacked in DSS 3.3.4 with both channels no background calibration off and saved as fits file. Loaded into Startools as “Linear, was Bayered, is not whitebalanced”. I think if you use this version of DSS it does not whitebalance. I then spent some considerable time with Startools trying to see what sort of image I could get out of the data. There is a lot more to Startools that I would really like to understand. A book along the lines of the examples and detail in the Unofficial manual would be something I would buy.
Whilst stacking I noticed that I have between 400 to 1400 stars detected using the 20% detection in DSS.
The attached is what I have achieved. My question is can this be improved by better processing in Startools or does my data need improvement; longer exposure times, guided tracking, or more frames?
Here is the DSS Stacked fits file;
https://btcloud.bt.com/web/app/share/invite/emAaBp63jJ
I would welcome the more experienced Startools to have a go at processing my data to see what can be achieved with this data.
John

IC1805 & IC1848.jpg (394.92 KiB) Viewed 7111 times

Workflow
StarTools 1.3.5.289
Thu Nov 10 17:58:50 2016
-----------------------------------------------------------
File loaded [G:\My Pictures Lightroom\Night Sky\2016\2016-11-07 Heart & Soul\Autosave LDBDFF.fts].
---
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside ROI Influence] set to [15 %]
--- Crop
Parameter [X1] set to [10 pixels]
Parameter [Y1] set to [10 pixels]
Parameter [X2] set to [4532 pixels (-10)]
Parameter [Y2] set to [3411 pixels (-10)]
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
--- Wipe
Parameter [Mode] set to [Correct Color & Brightness]
Parameter [UNKNOWN] set to [Yes]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [3 pixels]
Parameter [Drop Off Point] set to [100 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [75 %]
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside ROI Influence] set to [15 %]
--- Contrast
Parameter [Expose Dark Areas] set to [No]
Parameter [Compensate Gamma] set to [No]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [1 pixels]
Parameter [Aggressiveness] set to [75 %]
Parameter [Dark Anomaly Headroom] set to [15 %]
--- Color
Parameter [Cap Green] set to [No]
Parameter [Bias Slider Mode] set to [Sliders Reduce Color Bias]
Parameter [Style] set to [Scientific (Color Constancy)]
Parameter [LRGB Method Emulation] set to [Straight CIELab Luminance Retention]
Parameter [Dark Saturation] set to [2.00]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [170 %]
Parameter [Blue Bias Reduce] set to [1.26]
Parameter [Green Bias Reduce] set to [1.32]
Parameter [Red Bias Reduce] set to [1.00]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- Wavelet De-Noise
Parameter [Scale 1] set to [90 %]
Parameter [Scale 2] set to [90 %]
Parameter [Scale 3] set to [90 %]
Parameter [Scale 4] set to [90 %]
Parameter [Scale 5] set to [0 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Scale Correlation] set to [3]
Parameter [Color Detail Loss] set to [12 %]
Parameter [Brightness Detail Loss] set to [12 %]
Parameter [Grain Size] set to [4.5 pixels]
Parameter [Read Noise Compensation] set to [10.00 %]
Parameter [Smoothness] set to [75 %]
---
Parameter [Quality] set to [Medium]
Parameter [New Darker Than Old] set to [Yes]
Parameter [Grow Mask] set to [0 pixels]
Parameter [Neighbourhood Samples] set to [0]
Parameter [New Must Be Darker Than] set to [Off]
Parameter [Neighbourhood Area] set to [200 pixels]
--- Layer
Parameter [Layer Mode] set to [Subtract]
Parameter [Cap Mode] set to [Clip]
Parameter [Brightness Mask Mode] set to [Off]
Parameter [Filter Type] set to [Gaussian (Fg)]
Parameter [Blend Amount] set to [100 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Filter Kernel Radius] set to [1.0 pixels]
Parameter [Offset X] set to [0.0 pixels]
Parameter [Offset Y] set to [0.0 pixels]
Parameter [Brightness Mask Power] set to [1.00]
File saved [G:\My Pictures Lightroom\Night Sky\2016\2016-11-07 Heart & Soul\Star field.tiff].
Undo.
--- Contrast
Parameter [Expose Dark Areas] set to [No]
Parameter [Compensate Gamma] set to [No]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [1 pixels]
Parameter [Aggressiveness] set to [75 %]
Parameter [Dark Anomaly Headroom] set to [15 %]
--- Wavelet Sharpen
Parameter [Intelligent Enhance] set to [Yes]
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [100 %]
Parameter [Scale 3] set to [100 %]
Parameter [Scale 4] set to [100 %]
Parameter [Scale 5] set to [100 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Amount] set to [100 %]
Parameter [Small Detail Bias] set to [75 %]
--- Life
Parameter [Detail Preservation] set to [Min Distance to 1/2 Unity]
Parameter [Compositing Algorithm] set to [Power of Inverse]
Parameter [Inherit Brightness, Color] set to [Off]
Parameter [Output Glow Only] set to [No]
Parameter [Airy Disk Sampling] set to [128 x 128 pixels]
Parameter [Airy Disk Radius] set to [8 pixels]
Parameter [Glow Threshold] set to [12 %]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [50 %]
Parameter [Strength] set to [100 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
File loaded [G:\My Pictures Lightroom\Night Sky\2016\2016-11-07 Heart & Soul\Star field.tiff].
--- Layer
Parameter [Layer Mode] set to [Add]
Parameter [Cap Mode] set to [Clip]
Parameter [Brightness Mask Mode] set to [Off]
Parameter [Filter Type] set to [Gaussian (Fg)]
Parameter [Blend Amount] set to [100 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Filter Kernel Radius] set to [1.0 pixels]
Parameter [Offset X] set to [0.0 pixels]
Parameter [Offset Y] set to [0.0 pixels]
Parameter [Brightness Mask Power] set to [1.00]
--- Magic
Parameter [Mode] set to [Tighten]
Parameter [Mask Grow] set to [1 pixels]
Parameter [Iterations] set to [2 pixels]
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
File saved [G:\My Pictures Lightroom\Night Sky\2016\2016-11-07 Heart & Soul\IC1805 & IC1848.jpg].

[admin]

With your gear, you're producing some impressive data and from London no less.
"More exposures are always better", etc. but... look at what you got here! Nicely framed too.

You could try going a tad longer per frame, as I can see most of the brighter stars are not overexposing yet. A good rule of thumb is to have the sRGB stretched(!) histogram peak (which corresponds to the sky background) occur at roughly 1/3rd. My rough guess is you could probably go 80 seconds/frame or thereabouts. Maybe do a quick test to see how things look.

I'm pleasantly surprised with the coloring too, despite the LP filter (that IDAS filter is one of the least intrusive when it comes to color skew). No chromatic aberration to speak of either. It may be a modest setup, but it's clearly working well for you!

My (super simple, quick & lazy ) interpretation of your data suing 1.4.325;

Autosave LDBDFF.jpg (1.21 MiB) Viewed 7096 times

Log as follows;

--- Auto Develop
To see what we got. Blue-ish bias - light pollution I assume. Normally a blue bias is consistent with data that was not color balanced yet (yay!) (you would therefore use option 2 when loading)
--- Bin
Reducing noise somewhat.
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
--- Lens
To remedy star elongation towards the corners a little.
Parameter [Curvature Linked] set to [108.88 %]
--- Crop
Crop any remaining stacking artifacts.
Parameter [X1] set to [8 pixels]
Parameter [Y1] set to [8 pixels]
Parameter [X2] set to [2101 pixels (-8)]
Parameter [Y2] set to [1580 pixels (-8)]
--- Wipe
Getting rid of bias.
Default parameters, except Parameter [Dark Anomaly Filter] set to [6 pixels], just in case...
--- Auto Develop
Final stretch. RoI over heart nebula.
--- Color
Parameter [Cap Green] set to [To Yellow] (to remove a faint green band at the right edge)
Parameter [Dark Saturation] set to [3.20]
Parameter [Bright Saturation] set to [3.20]
Parameter [Saturation Amount] set to [123 %]
--- Life
Perfect use for the Isolate preset (no particular mask set) to push back noise and busy star field.
--- Wavelet De-Noise
Switching Tracking off.
Parameter [Scale 1] set to [85 %]
Parameter [Scale 5] set to [89 %]
Parameter [Grain Size] set to [17.3 pixels]
Parameter [Read Noise Compensation] set to [1.68 %]
Parameter [Smoothness] set to [82 %]

That's all.

I can see you're doing star reduction in your work flow. Just be careful with applying it as a blanket approach, as it can make your stars look stringy. Try the Life module trick I used above first to "push them back". Then try reducing only the "fatter" stars. If that fails apply it on all of them, but remember you can throttle the effect by going into the layer module afterwards and making a blend of the undo buffer and the star-size-reduced image.

FInally, try to do as many steps as possible while Tracking is still on (e.g. applying the Life module). You'll get better noise reduction that way since StarTools can take that operation into account (e.g. it will know that the background noise is being reduced by the Life module, allowing it to better target any other noise reduction).

Hope this helps!

[ecuador]

Wait, how does DSS not white-balance the image here? I've never seen a blue background when autodeveloping autodevelop with a DSS 3.3.4 image from RAW! Was it luck? DSS only white balances canons and Nikons but leaves Olympus alone?

[JLP]

Ivo Thanks a lot that is most helpful I will have another go using your recommendations.

[JLP]

Wait, how does DSS not white-balance the image here? I've never seen a blue background when autodeveloping autodevelop with a DSS 3.3.4 image from RAW! Was it luck? DSS only white balances canons and Nikons but leaves Olympus alone?

Without the filter I get red/orange for the first Auto Dev using DSS 3.3.4. When I was using DSS 3.3.3 I got an green/Yellow Auto Dev colour. I think the blue is due to the filter tint.

[JLP]

I have had a longer play with this image following your (Ivo) suggestions. I found it fiddly to get the right size ROI for the second AutoDev. If I do not bin I find that the second AutoDev gives me a better (darker) background albeit increased processing time. Because I am showing this image on the web I limit the size to about 1000 pixels wide. To do this I use the bin command in Startools. Is there merit doing noise reduction this way?

I struggled to see what your curvature adjustments were doing to the stars apart from a shift in the distribution of the stars and their relative position in the frame. Does this mean that my lens has an adverse effect on distortion of the image?

What really intrigues me is how you arrive at the adjustment amounts, particularly in the Color and Track modules. What magnification are you using and what are you looking at. I can see that my biggest learning is in the upping the grain size because I thought by doing so was reducing the sharpness of the image.

Here's what I have ended up with.

Ivo LDBDFF small.jpg (382.39 KiB) Viewed 7080 times

[admin]

I have had a longer play with this image following your (Ivo) suggestions. I found it fiddly to get the right size ROI for the second AutoDev. If I do not bin I find that the second AutoDev gives me a better (darker) background albeit increased processing time.

With low signal-to-noise data, AutoDev may start optimizing the allocated dynamic range in your chosen RoI for the noise grain (mistaking it for real detail). The "Ignore Fine Detail <" can help in such a case.
If you find the default value of 15% dynamic range allocation for the non-RoI area impacts you image (background) too much, reduce it (though note that 0% may cause clipping!)

Because I am showing this image on the web I limit the size to about 1000 pixels wide. To do this I use the bin command in Startools. Is there merit doing noise reduction this way?

Sure, you could use the Bin module to scale down for web viewing, which indeed would reduce any left-over visual noise. However, doing it as one of the first steps in your processing flow will give StarTools much better signal (e.g. less noise) to work with across all modules, allowing you to achieve better results.

I struggled to see what your curvature adjustments were doing to the stars apart from a shift in the distribution of the stars and their relative position in the frame. Does this mean that my lens has an adverse effect on distortion of the image?

Some star elongation exists in the corners compared to the center - your stars aren't quite round in those areas. This is a tell-tale sign of coma. A field flattener would correct this, however this can be mitigated to some degree using the Lens module which models the distortion and reverses it (though it's preferable to do something similar before stacking).

What really intrigues me is how you arrive at the adjustment amounts, particularly in the Color and Track modules. What magnification are you using and what are you looking at.

For the Color module, it's purely taste and eyeballing waht your data lets you get away with (or what it needs).
The "?" button explains all; The bright/dark saturation settings introduce or remove color in the highlights/shadows, while the Saturation amount... governs the amount of color saturation.

With very noisy datasets, color noise can sometimes really become noticeable in the shadows - it can help backing off on the Dark Saturation in those cases.
Deep Sky Stacker can cause color artifacts in the highlights depending on how/if it clipped them, or how it well it aligned the color channels. Color fringes around bright star cores that show one side blue and the opposite side red are a common sighting in that case. Reducing the color saturation in the highlights can make these fringes less noticeable.

I can see that my biggest learning is in the upping the grain size because I thought by doing so was reducing the sharpness of the image.

Determining the Grain Size in the first screen of the Denoise module is done by increasing that parameter until you can no longer see grain at any scale. It's purely a visual aid. Your image won't be blurred like that.
In the second screen, you can still change the grain size parameter (you just don't get the visual aid).

Here's what I have ended up with.

Ivo LDBDFF small.jpg

Very, very nice! A solid improvement.

[JLP]

Once again Thanks very much Ivo for your explanations and time to reply