Wavelet denoise introducing dark artefacts in stars

Bugs, glitches and unexpected behaviour.

Wavelet denoise introducing dark artefacts in stars

Postby almcl » Tue Mar 19, 2019 12:04 pm

Pretty sure I've read something about this before but can't find it at the moment.

The Wavelet denoise module that's called when tracking is switched off is introducing dark patches in the center of some of my larger stars (cropped images below showing the effect).

Can't remember what the solution to this was, so please could someone with a better memory remind me?

black dots before.jpg
before wavelet denoise runs
black dots before.jpg (44.52 KiB) Viewed 906 times


black dots after.jpg
After denoise has run
black dots after.jpg (37.33 KiB) Viewed 906 times
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
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Re: Wavelet denoise introducing dark artefacts in stars

Postby admin » Thu Mar 21, 2019 4:19 am

Hi,

What version of StarTools is this?
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Re: Wavelet denoise introducing dark artefacts in stars

Postby almcl » Thu Mar 21, 2019 5:10 am

Version 1.4.344, running under Windows 7 pro 64 bit.
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
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Re: Wavelet denoise introducing dark artefacts in stars

Postby admin » Thu Mar 21, 2019 5:58 am

Hmmm... that's a bit odd...

Would you be able to dig up the settings you used from StarTools.log?
It only appears to happen in areas that are over exposed (e.g. completely white).
The problem should be easy to fix by just masking back in the non-denoised star cores.

You can generate a mask;

Mask > Auto, set Selection Mode to Highlights > Threshold, set Threshold to 99.99 (e.g. click the minus button once).

Even the 'Fat Stars' preset may do the trick.

Then, in the Layer module, click Undo > Foreground and the star cores should be restored.
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Re: Wavelet denoise introducing dark artefacts in stars

Postby almcl » Thu Mar 21, 2019 8:08 am

Here's the log (with masks removed):
-----------------------------------------------------------
StarTools 1.4.344
Mon Mar 18 21:02:02 2019
-----------------------------------------------------------
File loaded [E:\Astronomy\2018\2018-04-20 Markarian's chain\Autosave005.fts].
Image size is 5208 x 3476
---
Type of Data: Linear, was not Bayered, or was Bayered + white balanced
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside RoI Influence] set to [15 %]
Parameter [RoI X1] set to [0 pixels]
Parameter [RoI Y1] set to [0 pixels]
Parameter [RoI X2] set to [5208 pixels (-0)]
Parameter [RoI Y2] set to [3476 pixels (-0)]
--- Crop
Parameter [X1] set to [29 pixels]
Parameter [Y1] set to [87 pixels]
Parameter [X2] set to [4676 pixels (-532)]
Parameter [Y2] set to [3409 pixels (-67)]
Image size is 4647 x 3322
--- Bin
Parameter [Scale] set to [(scale/noise reduction 70.71%)/(200.00%)/(+1.00 bits)]
Image size is 3285 x 2348
--- Wipe
Parameter [Mode] set to [Correct Color & Brightness]
Parameter [Temporary AutoDev] set to [Yes]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [4 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 %]
Parameter [RoI X1] set to [1179 pixels]
Parameter [RoI Y1] set to [1505 pixels]
Parameter [RoI X2] set to [1227 pixels (-2058)]
Parameter [RoI Y2] set to [1551 pixels (-797)]

Mask used (BASE64 PNG encoded)


--- Life
Parameter [Detail Preservation] set to [Linear Brightness Mask]
Parameter [Compositing Algorithm] set to [Multiply, Gamma Correct]
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 [64 pixels]
Parameter [Glow Threshold] set to [0 %]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [100 %]
Parameter [Strength] set to [114 %]
Parameter [Mask Fuzz] set to [40.0 pixels]

Mask used (BASE64 PNG encoded)



--- HDR
Parameter [Small Detail Precision] set to [Max]
Parameter [Channels] set to [Brightness Only]
Parameter [Algorithm] set to [Optimize Soft]
Parameter [Dark/Bright Response] set to [Full]
Parameter [Detail Size Range] set to [21 pixels]
Parameter [Strength] set to [1.2]
Mask used (BASE64 PNG encoded)



Mask used (BASE64 PNG encoded)

--- Wavelet Sharpen
Parameter [Structure Size] set to [Large]
--- 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 [8.0 pixels]
Parameter [Amount] set to [100 %]
Parameter [Small Detail Bias] set to [75 %]
Mask used (BASE64 PNG encoded)

--- HDR
Parameter [Small Detail Precision] set to [Max]
Parameter [Channels] set to [Brightness Only]
Parameter [Algorithm] set to [Optimize Hard]
Parameter [Dark/Bright Response] set to [Full]
Parameter [Detail Size Range] set to [21 pixels]
Parameter [Strength] set to [1.2]
--- 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 %]
--- Life
Parameter [Detail Preservation] set to [Linear Brightness Mask]
Parameter [Compositing Algorithm] set to [Multiply, Gamma Correct]
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 [3 pixels]
Parameter [Glow Threshold] set to [0 %]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [100 %]
Parameter [Strength] set to [80 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- 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 [200 %]
Parameter [Blue Bias Reduce] set to [1.69]
Parameter [Green Bias Reduce] set to [1.00]
Parameter [Red Bias Reduce] set to [2.22]
Parameter [Mask Fuzz] set to [1.0 pixels]
Undo
Image size is 3285 x 2348
--- Color
Parameter [Cap Green] set to [To Yellow]
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 [200 %]
Parameter [Blue Bias Reduce] set to [1.69]
Parameter [Green Bias Reduce] set to [1.00]
Parameter [Red Bias Reduce] set to [2.22]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- Wavelet De-Noise
Parameter [Filter Type] set to [Distance Weighted Outlier Rejection]
Parameter [Grain Size] set to [5.0 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 [6]
Parameter [Color Detail Loss] set to [12 %]
Parameter [Brightness Detail Loss] set to [12 %]
Parameter [Grain Size] set to [5.0 pixels]
Parameter [Read Noise Compensation] set to [Off]
Parameter [Smoothness] set to [75 %]
File saved [E:\Astronomy\2018\2018-04-20 Markarian's chain\AS5 b.tiff].
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
almcl
 
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Location: Shropshire. UK

Re: Wavelet denoise introducing dark artefacts in stars

Postby almcl » Thu Mar 21, 2019 8:22 am

Tried the Mask solution you mentioned, but, perhaps as this is post tracking switch off, can't get Fat Stars or Layer Module 'undo background' to perform as neither seems to be active?

It's not a great problem and I fixed it in PhotoPaint quite quickly with the clone brush.

Incidentally, looking at the stacked image before processing, I can't find any stars that are completely saturated although quite a few are close:
sat.jpg
sat.jpg (14.65 KiB) Viewed 882 times


Is it my processing that's causing the saturation and this problem?
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
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Re: Wavelet denoise introducing dark artefacts in stars

Postby admin » Thu Mar 21, 2019 9:37 am

Many thanks for attaching that! I really can't see anything suspect... :think:
almcl wrote:Tried the Mask solution you mentioned, but, perhaps as this is post tracking switch off, can't get Fat Stars

Fat stars indeed requires Tracking to still be on, apologies - I should've mentioned that.
or Layer Module 'undo background'

This one should definitely be available! ("Undo>Bg"). It will copy the undo buffer to the background.

Incidentally, looking at the stacked image before processing, I can't find any stars that are completely saturated although quite a few are close:

Aha! Well spotted. This could definitely be the problem. It certainly looks like some of your star cores should most definitely be overexposing, yet they are not.

How are the individual frames acquired and treated?
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Re: Wavelet denoise introducing dark artefacts in stars

Postby almcl » Thu Mar 21, 2019 11:40 am

Individual subs are Canon raw files (.CR2) captured using Astrophotography Tool. Stacked in Deep Sky Stacker with bias and flat frames with all the options unchecked. If you need the data I can put the subs and master calibration files in a Dropbox folder?

I think the Undo Background issue arose because I loaded the saved image rather than repeated the previous processing.

Here are my DSS settings:
DSS Settings.jpg
DSS Settings.jpg (60.92 KiB) Viewed 876 times
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
almcl
 
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Location: Shropshire. UK

Re: Wavelet denoise introducing dark artefacts in stars

Postby admin » Thu Mar 21, 2019 12:12 pm

Much appreciated!

almcl wrote:Individual subs are Canon raw files (.CR2) captured using Astrophotography Tool. Stacked in Deep Sky Stacker with bias and flat frames with all the options unchecked. If you need the data I can put the subs and master calibration files in a Dropbox folder?


I'm thinking it's not so much the data. Looking at the star coloring again, it does appear something introduced some color fringing/color channel mismatch somewhere along the line. You can see it in the single star you have the dropper over as well; the top is bluer than the sides. This is not LRGB data, it's just from a DSLR so I'm not sure here the channel mismatch would come from (with a DSLR all channels are recorded at the same time obviously). Perhaps something in your optical train?

The color signature (orange vs cyan) is a typical blue+green vs rd+green mismatch. This is where the pixels exist for every blue or red pixel, however blue pixels do not exist for red pixel, nor vice versa.

Do you have this issue all the time? Does stacking with a different debayering algorithm (e.g. AHD) help at all?

I think the Undo Background issue arose because I loaded the saved image rather than repeated the previous processing.

Ah, yes that would cause that; there would be no "previous image" in the undo buffer in that case.
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Re: Wavelet denoise introducing dark artefacts in stars

Postby almcl » Thu Mar 21, 2019 12:56 pm

The camera is astro modded to allow more of the red through and, for that image, was attached to a Canon 200 mm EF f2.8 II lens. Focusing to get the 'extra' red tight with the other channels is always a bit of a compromise, even using live view and 10 x magnification on the laptop screen.

I'll try a re-stack using AHD debayering
Skywatcher 200P with an astro modded Canon 700d, cls ccd filter, field flattener, guided by ASI 120, PHD2
almcl
 
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Location: Shropshire. UK


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