problem with noise

[1074j]

Ivo,
I've noticed a problem for some time when using denoise. It leaves behind many single dark pixels, mainly in the darker areas of the image. The only way to get rid of them is to turn up the scale 3-5 to higher values, which then removes too much detail. Attached is an example of this. The image is enlarged and contrast stretched out in order to see this better. This image also had deconv and sharping applied. I normally use scale1=100, scale2=90 scale3=50 scale4=0 scale5=0. Maybe I'm using denoise incorrectly? Thanks for any help.
Lex

Original image http://www.astrobin.com/full/89653/B/?real=&mod=

Another example-you can see the dark pixels mainly on the right side http://www.astrobin.com/full/89774/B/

[admin]

Hmmm... that's odd. Could you perhaps share the data (or a crop of the data) and your processing log? It would bemuch appreciated!

[1074j]

Sorry I haven't gotten back to you until now. The fit file is here:
http://www.atmo.arizona.edu/~leuthold/L.fit


-----------------------------------------------------------
StarTools 1.3.5.275
-----------------------------------------------------------
File loaded [F:\astro\ngc3344\Lv2.tiff].
---
File loaded [F:\astro\ngc3344\L.fit].
---
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.00]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [70.50 %]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [Off]
--- Crop
Parameter [X1] set to [4 pixels]
Parameter [Y1] set to [4 pixels]
Parameter [X2] set to [1371 pixels (-5)]
Parameter [Y2] set to [1094 pixels (-6)]
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.00]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [84.60 %]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [Off]
--- Deconvolution
Parameter [Image Type] set to [Deep Space]
Parameter [Mask Behavior] set to [De-ring Mask Gaps, Hide Result]
Parameter [Radius] set to [4.0 pixels]
Parameter [Iterations] set to [6]
Parameter [Regularization] set to [1.00 (optimal noise and detail)]
Parameter [Mask Fuzz] set to [8.0 pixels]
--- 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 [200 %]
Parameter [Small Detail Bias] set to [75 %]
--- Wavelet De-Noise
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [97 %]
Parameter [Scale 3] set to [83 %]
Parameter [Scale 4] set to [68 %]
Parameter [Scale 5] set to [50 %]
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 [Redistribution Kernel] set to [4.5 pixels]
Parameter [Read Noise Compensation] set to [Off]
Parameter [Smoothness] set to [75 %]

Hmmm... that's odd. Could you perhaps share the data (or a crop of the data) and your processing log? It would bemuch appreciated!

[admin]

Hi,

I used your data and log to recreate something similar to what you posted before. Is this the issue you are experiencing?

anim.gif (313.07 KiB) Viewed 12118 times

If so, then, as you can see, StarTools merely leaves in what it thinks is detail. Indeed, the specks that it leaves in stands out from the random noise and must almost certainly be introduced somewhere down the line (whether genuine detail or issues with the flat frames).
If StarTools picks up such detail and you believe the detail is clumped together read noise (statisctically unlikely but can't be ruled out), then increase the Read Noise Compensation parameter. It will attack read noise induced noise specifically.
If this does not illustrate the issue you're experiencing, then do let me know and we'll do some more sleuthing!

[1074j]

Yes, this is about what I see. I did try turning up RNC to 10% and it did help quite a bit and will use this in the future. Thanks!
Lex

Hi,

I used your data and log to recreate something similar to what you posted before. Is this the issue you are experiencing?

anim.gif

If so, then, as you can see, StarTools merely leaves in what it thinks is detail. Indeed, the specks that it leaves in stands out from the random noise and must almost certainly be introduced somewhere down the line (whether genuine detail or issues with the flat frames).
If StarTools picks up such detail and you believe the detail is clumped together read noise (statisctically unlikely but can't be ruled out), then increase the Read Noise Compensation parameter. It will attack read noise induced noise specifically.
If this does not illustrate the issue you're experiencing, then do let me know and we'll do some more sleuthing!

[admin]

Awesome!

[1074j]

I have to change my answer from a "yes" to RNC helps to "sometimes". Here's another example from another user on astrobin that I found. Look at the darker areas in the bottom right corner especially, and you can see all the dark specks. When I still have the problem, I typically increase the denoise sliders and also increase "smoothness". Sometimes this works OK, sometimes it blurs too much. I'm not really bothered by it as I can usually work around the problem, but I though you may want to see another example from a different user.
Lex

http://www.astrobin.com/full/97233/0/?real=&mod=

Yes, this is about what I see. I did try turning up RNC to 10% and it did help quite a bit and will use this in the future. Thanks!
Lex

Hi,

I used your data and log to recreate something similar to what you posted before. Is this the issue you are experiencing?

anim.gif

If so, then, as you can see, StarTools merely leaves in what it thinks is detail. Indeed, the specks that it leaves in stands out from the random noise and must almost certainly be introduced somewhere down the line (whether genuine detail or issues with the flat frames).
If StarTools picks up such detail and you believe the detail is clumped together read noise (statisctically unlikely but can't be ruled out), then increase the Read Noise Compensation parameter. It will attack read noise induced noise specifically.
If this does not illustrate the issue you're experiencing, then do let me know and we'll do some more sleuthing!