A more subtle M27

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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maxchess
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Joined: Fri Mar 22, 2019 1:07 pm
Location: Guildford, UK

A more subtle M27

Post by maxchess »

I need to learn how to use Startools in a more subtle manner. I recently processed an M27 stacked image in Startools and although it brought out more detail it lost the subtlety of the original.
Below is a comparison, the top file is M27 straight from DSS. I just opened it in Startools and saved as a Jpeg. The second one is the image after I processed it in Startools. There is more detail, but its lost is subtlety and ethereal feel.
Also the background star field in the original is sparse and seems to have less noise and is altogether more pleasing.
I have been using Startools for about a year and usually the processed images are a lot better, but I still struggle with getting the feint nebulosity in some images.
In this dropbox you will find the log file, the original fts from DSS and the two full images, processed and not.
https://www.dropbox.com/sh/7h3cfaiwmgu6 ... AHn3a?dl=0
M27 Before Processing
M27 Before Processing
M27Unprocessed.jpg (234.03 KiB) Viewed 1898 times
M27 after Startools
M27 after Startools
M27v1.jpg (392.67 KiB) Viewed 1898 times
The imaging was taken with an ASI178MC (uncooled) 80 x 60 secs + 20 Darks + 20 Flats


Any tips or advice gratefully received.
Max
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Re: A more subtle M27

Post by admin »

Hi Max,

Fist off, can you confirm for me the output from DSS has not been stretched or meddled with in any way? The detail is very bright, with nary any bias/skyglow visible. It makes a little suspicious as to the linearity of this. It looks like the dataset has been meddled with beforehand. I could be wrong though.

Though "ethereal" and "subtle" can mean different things to different people, the Life module was designed to drastically transform the "feel" of an image.
I processed your image in StarTools 1.5 (just released!) as follows ;
--- Crop
Parameter [X1] set to [482 pixels]
Parameter [Y1] set to [229 pixels]
Parameter [X2] set to [1975 pixels (-1121)]
Parameter [Y2] set to [1477 pixels (-603)]
Image size is 1493 x 1248
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
Image size is 746 x 624
--- Wipe
Parameter [Dark Anomaly Filter] set to [4 pixels]
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [5.0 pixels]
Parameter [Outside RoI Influence] set to [25 %]
Parameter [RoI X1] set to [277 pixels]
Parameter [RoI Y1] set to [226 pixels]
Parameter [RoI X2] set to [461 pixels (-285)]
Parameter [RoI Y2] set to [404 pixels (-220)]
--- HDR
Parameter [Algorithm] set to [Reveal DSO Core]
Parameter [Dark/Bright Response] set to [Full]
Parameter [Detail Size Range] set to [1000 pixels]
Parameter [Strength] set to [1.2]
--- Color
Parameter [Dark Saturation] set to [5.00]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [100 %]
--- Life
Isolate preset with tweaks;
Parameter [Compositing Algorithm] set to [Multiply, 2x Gamma Correct]
Parameter [Saturation] set to [273 %]
Parameter [Strength] set to [49 %]
--- Wavelet De-Noise
Parameter [Filter Type] set to [Distance Weighted Outlier Rejection]
Parameter [Grain Size] set to [9.1 pixels]
--- Wavelet De-Noise
Default.
Autosave(1).jpg
Autosave(1).jpg (93.77 KiB) Viewed 1883 times
Is this more what you're after?
Ivo Jager
StarTools creator and astronomy enthusiast
maxchess
Posts: 17
Joined: Fri Mar 22, 2019 1:07 pm
Location: Guildford, UK

Re: A more subtle M27

Post by maxchess »

Ivo,

Thanks very much for doing that. Yes I can confirm that the fts file came straight out of DSS with no processing.
I have out the original data in dropbox here: https://www.dropbox.com/sh/5y3v96zfaw2g ... Og7xa?dl=0

This contains 80 x 60 secs lights + 20 Darks + 20 Flats. these are 16 bit images, DSS Bayer setting is RGGB
The image was taken with an ASI178MC (uncooled) which has a very small pixel size of 2.4 and a QE of 81% . It uses Sonys IMX178 chip which was originally intended for security cameras requiring high sensitivity. Like you I was surprised by the brightness of the image compared to using a DSLR. The gain was set at 255 which is mid range. I found that if I increased the exposure or the gain it blew out the highlights. I might try again with lower gain and longer exposure to see if it improves the dynamic range. For a very cheap camera I am impressed by the results. I use it with a ES102 triplet, FL= 700 which is a good match. It gives an FOV equivilent to a DSLR on a C8 SCT.

Your example processing is very helpful as a standard process.
Could you tell me if you used a mask for Wipe or for Isolate and if so, do you make it tight to the object or much wider?

All the best
Max
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Re: A more subtle M27

Post by admin »

maxchess wrote:I found that if I increased the exposure or the gain it blew out the highlights. I might try again with lower gain and longer exposure to see if it improves the dynamic range.
Do you know what the "native"/recommended gain is? The stars are indeed blowing out, so either the exposure times are quite long, or the gain is set too high.
The (possible) issue with acquiring data close to filling up the available dynamic range is also that some sensors have a non-linear response at those levels. You'll want to avoid that.
The dataset indeed looks nice and clean though. :thumbsup:
Could you tell me if you used a mask for Wipe or for Isolate and if so, do you make it tight to the object or much wider?
No mask was used for the Life module. A mask is generally not needed or desirable. I would only use a mask if the data cannot stand on its own and you are trying to "rescue" an object from something otherwise unusable (it can be construed as borderline "doctoring" the image if a freehand mask is used). Your dataset is quite good, so there is no need for that here.

Cheers!
Ivo Jager
StarTools creator and astronomy enthusiast
maxchess
Posts: 17
Joined: Fri Mar 22, 2019 1:07 pm
Location: Guildford, UK

Re: A more subtle M27

Post by maxchess »

Ivor,
Based on your comments and the idea that less is more and to avoid doctoring I tried again with minimal, but effective processing. (I attach the log file, but version 1.5 seems to have put a lot of rubbish characters, when viewed in a text editor). (tried to upload log but got The extension log is not allowed.
The result brought out the image, but left it looking more natural (personal view), but great tool. Got the result I wanted.
M27v4.jpeg
M27v4.jpeg (404.22 KiB) Viewed 1834 times
My processing was:
File loaded [Z:\M27ASI784Light60\Autosave.fits].
Image size is 3096 x 2080
---
Type of Data: Linear and was Bayered, but not whitebalanced
--- Auto Develop
# Autodev just to identify stacking artifacts/ ampglow for cropping
Parameter [Ignore Fine Detail <] set to [2.0 pixels]
Parameter [Outside RoI Influence] set to [50 %]
Parameter [RoI X1] set to [0 pixels]
Parameter [RoI Y1] set to [0 pixels]
Parameter [RoI X2] set to [3096 pixels (-0)]
Parameter [RoI Y2] set to [2080 pixels (-0)]
--- Crop
Parameter [X1] set to [79 pixels]
Parameter [Y1] set to [66 pixels]
Parameter [X2] set to [2790 pixels (-306)]
Parameter [Y2] set to [1872 pixels (-208)]
Image size is 2711 x 1806
# No bin left full size
--- Wipe
Parameter [Mode] set to [Correct Color & Brightness]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [1 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [20 %]

#Note low aggressiveness, also after Wipe the image seems to have returned to its pre-stretch state
# It looked good so I did no further Autodev
# Fat star inverted mask, shrunk then just DEcon before end tracking and save:

--- Deconvolution
Parameter [Image Type] set to [Deep Space]
Parameter [Mask Behavior] set to [De-ring Mask Gaps, Hide Result]
Parameter [Radius] set to [1.5 pixels]
Parameter [Iterations] set to [6]
Parameter [Regularization] set to [1.00 (optimal noise and detail)]
Parameter [Mask Fuzz] set to [4.0 pixels]
--- Wavelet De-Noise
Parameter [Filter Type] set to [Distance Weighted Outlier Rejection]
Parameter [Grain Size] set to [2.0 pixels]
--- Wavelet De-Noise
Parameter [Scale 1] set to [95 %]
Parameter [Scale 2] set to [95 %]
Parameter [Scale 3] set to [95 %]
Parameter [Scale 4] set to [95 %]
Parameter [Scale 5] set to [0 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Scale Correlation] set to [6]
Parameter [Color Detail Loss] set to [12 %]
Parameter [Brightness Detail Loss] set to [12 %]
Parameter [Grain Dispersion] set to [2.0 pixels]
Parameter [Non-linear Response <] set to [Off]
Parameter [Smoothness] set to [65 %]
File saved [Z:\M27ASI784Light60\M27v4.tiff].
File saved [Z:\M27ASI784Light60\M27v4.jpeg].

# Resultant file size a lot smaller than previous more processed version

Regards

Max
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Re: A more subtle M27

Post by admin »

Great to hear you've found a rendition you are happy with Max! :thumbsup:
(by the way, the rubbish characters is actually a BASE64 PNG representation of your mask, see here on how to convert them back to a mask)
Ivo Jager
StarTools creator and astronomy enthusiast
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