Where is this fog coming from?

[khobar95]

Hi Folks,

I'm new to StarTools.

I'm trying to process M31 I shot the other night, and ST is doing an excellent job of pulling out faint detail. Unfortunately, the effort is ruined because of some weird fogging.

I stack in DSS and save as FITS with changes embedded but not applied.

The below image is the FITS brought into ST's "AutoDev" module after a slight cropping on the right edge. I used "Linear, was Bayered, is not whitebalanced, but the result is the same regardless of how I open it.

I don't see this fog on any of the original frames, nor do I see it when I bring the image generated from DSS into Photoshop and crank the lighting/saturation. So, any idea where this is coming from?

[khobar95]

This is M42 essentially handled the same way. This time, however, instead of blue I get pink.

[Cheman]

khobar
are these before or after running Wipe?
Che

[khobar95]

Hi Che,

Could very well be. Since I'm new to ST, I'm strongly favoring unfamiliarity/noob as the likely cause. I've been trying to reproduce the exact results I posted, but I've not quite managed to get it right. The closest I've come is bringing my FTS into the "Wipe" module and turning "Temporary AutoDev" on - that produces yellow and pink areas on the image. After I click "Keep" the intensity drops dramatically, but I can still see the distortion.

Bringing the FTS into the AutoDev module does not produce the color fogging, so I must have been mistaken yesterday.

[Cheman]

the intensity drops when you hit keep because that is a "TEMPORARY" AUTO DEV. Try this, open your file, crop off the very edges to make sure there are no stacking artifacts. then open wipe. Use temp auto dev, and let wipe do its thing. If you see blue or pink, there are some tweaks to the wipe that you can do. I'm not at a computer that has ST installed on it right now, but later, when I can see what I'm talking about, I'll fill you in and we'll see if it helps. From my very poor memory . it was the dark anomaly filter(bump it up one unit at a time) or the agressive setting, or maybe acombination of the two. It works for my images that show a blue haze in certain areas, have not seen the pink haze. Also, if you could upload your stacked file to dropbox or googledrive or where ever, I can take a look see.
Che

[admin]

the intensity drops when you hit keep because that is a "TEMPORARY" AUTO DEV. Try this, open your file, crop off the very edges to make sure there are no stacking artifacts. then open wipe. Use temp auto dev, and let wipe do its thing. If you see blue or pink, there are some tweaks to the wipe that you can do. I'm not at a computer that has ST installed on it right now, but later, when I can see what I'm talking about, I'll fill you in and we'll see if it helps. From my very poor memory . it was the dark anomaly filter(bump it up one unit at a time) or the agressive setting, or maybe acombination of the two. It works for my images that show a blue haze in certain areas, have not seen the pink haze. Also, if you could upload your stacked file to dropbox or googledrive or where ever, I can take a look see.
Che

^ this guy

Looks like it's caused by 'dark anomalies'; data that is not 'real' and is darker than the real background. Crop away or mask out these dark anomalies. And the 'dark anomaly filter' can take care of the smaller ones (dead pixels, etc.). It's caused by not calibrating your data correctly (or at all).

[khobar95]

Oh I know it's temporary.

For stacking, I used the "Intersect" mode to help eliminate artifacts caused by frame misalignment. But ST still warns about potential stacking artifacts, so I cropped off the edges. The color effects were after this was done.

There was a dust spot or two on the sensor while I was imaging.

Admin - calibrating my data? Please explain - the only "calibration" I've done is with darks and flats.

After hibernating my computer, I came back this morning, cropped the image down further as suggested, and the result is a pink/white/light grey fog over the lower 1/4 of the image.

I closed ST, reopened ST, opened the image in question, cropped it even more than I had moments before, and now I have something resembling the M42 shot except it's blue upper left and lower right, and purple upper right and lower left. (when I bring the tiff into PS, only the blue really shows). I then started again from scratch and tried to closely match the original cropping - see attached.

The file in question is here: http://richardpnixon.com/m31_102514_3.FTS

Thanks very much for the help!

[MrMxyzptlk]

I hope you don't mind, I took a run on your image. I saw your artifacts too when I did wipe, so I cropped out a few pixels from the margins (with StarTools). I'm pretty sure you can do a better process on this data, I did not try very hard too bring out max details (like I did not use the HDR modul to try and bring out more details). I think you need a little bit more data on this, or maybe when you captured there was some humidity in the air. But the data is pretty OK.
Here is my process (the UNKNOWN parameter in the WIPE module is Temporary AutoDev):

File loaded [E:\Astronomy\Process\m31_102514_3.FTS].
---
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside ROI Influence] set to [15 %]
--- Crop
Parameter [X1] set to [38 pixels]
Parameter [Y1] set to [42 pixels]
Parameter [X2] set to [4835 pixels (-66)]
Parameter [Y2] set to [3108 pixels (-72)]
--- 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 [4 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [75 %]
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [2.2 pixels]
Parameter [Outside ROI Influence] set to [5 %]
--- Deconvolution
Parameter [Image Type] set to [Deep Space]
Parameter [Mask Behavior] set to [De-ring Mask Gaps, Hide Result]
Parameter [Radius] set to [2.5 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 %]
--- 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 [9.80]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [100 %]
Parameter [Blue Bias Reduce] set to [1.29]
Parameter [Green Bias Reduce] set to [1.17]
Parameter [Red Bias Reduce] set to [1.17]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- 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 [8 pixels]
Parameter [Glow Threshold] set to [4 %]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [50 %]
Parameter [Strength] set to [50 %]
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 [60 %]
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 [6.0 pixels]
Parameter [Read Noise Compensation] set to [Off]
Parameter [Smoothness] set to [75 %]
Undo.
--- 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 [60 %]
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 [7.5 pixels]
Parameter [Read Noise Compensation] set to [50.00 %]
Parameter [Smoothness] set to [75 %]
File saved [E:\Astronomy\Process\m31_102514_3.tiff].

Maybe this helps?

m31_102514_3.jpg (306.51 KiB) Viewed 9438 times

[khobar95]

Mind? On the contrary, I am extremely pleased that you would process the data.

I'm trying to image from a "white" zone and have been experimenting with differing ISO's and exposure times. I'm using my wife's Nikon D5100 and it generally does a good job. You mentioned humidity - maybe, but I think it's more likely dust haze. Our skies are not great.

I am really impressed with what you did, especially getting rid of the background noise. Looking at your variables I can't help but wonder how you came about choosing those particular values? I've been experimenting with what Cheman posted Sep 28, 2014 which is what led to what I posted previously.

I'm trying to improve on what turned out to be my first attempt at M31 I shot when I got my new scope (see attached, 32 x 300sec ISO200 + 9 x 30-180sec ISO200). I was disappointed with the results at first - I could not find color or good detail, but someone on Cloudynights where I posted it said they thought the data was actually pretty good and suggested I try ST. I worked on it with DSS and PS (I didn't have ST yet) and found the color and detail, but the stars at the edges were not good due to lack of field flattener. I have since added ST and a FF and have been trying to get at least as good as I started with. The current image I'm wanting to work with is from 48 x 300sec ISO200, if that matters)

What you produced is a huge step in the right direction, and I thank you.

[MrMxyzptlk]

From a white zone I think a CLS-CCD filter would help you, although I don't know if there is such a thing for Nikon, most probably there is. Dust haze might be a possibility too for your data.

I'm using StarTools only for a few months so I'm learning too, I watched all the tutorials, I read the forums here and also experimented myself, many times I process the same raw data 5-6 times with different settings too see how they affect my image. Like I saw in your data some dust on the lens or something that is producing a little blob thingy so when I did WIPE I increased the Dark Anomaly Filter to 4 pixels to try and tell WIPE to ignore those. I usually do margin crop in StarTools when the software tells me there are stacking artefacts, or when I see exactly does strange halos what you have linked. I usually get these artifacts when I'm stacking with DSS, when I stack with Iris I don't have such problems, but with Iris I get the black bars, a clear evidence of the stacking artifacts. I like IRIS stacking better, but it's harder and there are cases when I get a faster and pretty good result with DSS. I used BIN, because I saw the noise on the picture, so that I can get rid of some of the noise, I used ROI on the middle of the image when I did Auto Develop a second time around, Deconvolution was left with mostly the standard settings with an automated star mask, I just took out from the auto star mask the middle of the galaxy, and set the pixel radius to 2.5 to get out some more details. The Color and Wavelet steps is more taste based, so I tried a few settings until I got something I liked (although I don't like the final color balance, but it's not all that bad, I say I could have been playing around a little bit more with the values) and on the Life module I made the background a little bit darker.

I'm curious when Ivo wakes up (admin) what will he do with your data He helped me already a few times to point me in the right direction.