Cyan stars, is this normal?

[cytan299]

Hi guys,
I've used Startools for a quite a while now and it's a great little program!

However, I'm having some problems with color. For example my M31 photo after colorization shows cyan stars when I think it should be more white. Is there a way of getting more white stars or is this what it's supposed to look like?

Photo was taken with an STF8300C (OSC) with a Hutech LPS filter.


Any help appreciated.

P.S. This is a first pass at processing M31, there's still some noise to be gotten rid of.

cytan

[Rkonrad]

I'm an intermediate user but perhaps I can help. Looks also like there is a lot of green happening in your image as well. I also noticed large band on the right hand edge of your image. If my image looked like that I would assume the wipe module didn't accurately do its job. Did you crop out the artifacts at the edges of your screen before you "wiped"? Nice detail there otherwise. Without seeing the data it's pretty hard for us to help. Could you send your stacked tiff or fits via Dropbox etc and I'd be happy to look at it.

Cheers. Richard

[cytan299]

Hi Richard,
Thanks for having a look. This is just my first pass at working on the image. There is a lot of noise pollution and noise in the data -- that can't be helped because I live in basically a red zone. My suspicion about the cyan is that it comes from the LPS filter. But if somebody can do better, I'd really appreciate it.

The fit file is here:
https://www.dropbox.com/s/1yrwqj9wlv9i4 ... 1.fit?dl=0

And for your convenience, here's the mask that I made for the image:
https://www.dropbox.com/s/blxysqok276hb ... .tiff?dl=0

I'd be glad to see what you can do with it!

cytan

[Rkonrad]

HI Cytan

There appears to be quite a lot of dark anomalies in your data. That may account for weird colours and some greens which I was not completely able to avoid. The toughest part was the wipe.

1. I did a healthy crop on the image especially focussing on the bottom edge.
2. With "wipe" I first did a vignette which cleared most of the issues up, then did a second pass with a standard wipe.
3. At the colour module, to avoid the parts of the image that might confuse things, I lassoed the central part of the galaxy (about 2/3rds), then subtracted the stars within that (though I don't know if that was necessary). With this I "sampled" and then masked the whole image to apply the colour balance setting. I had to cap green to yellow and then reduced the green a bit further.
4. At the denoise I noticed that when I increased smoothing the green came out again in the nebulosity just around the galaxy. Here I further reduced the green but probably affected the general colour.

I did a bunch of other things but the above points were the most important regarding colour accuracy etc.

https://www.flickr.com/gp/rkonrad/Uoe23V (all my flickr posts are private)

I'd love to know your specs - what was the camera, scope etc - just for my personal interest. I just use a zoom lens for the little that I do and looking forward to using an actual telescope.

Cheers Richard

[cytan299]

Hi Richard,
Thanks for working on my data! Looks pretty good but I think the cyan stars are still there. My guess is that the LPS filter just messes up the color spectrum. Perhaps there are ways outside startools to overcome this problem.

Can you post your log so that I can follow what you did? I'll probably rework it over the weekend.

The specs for taking this this picture:
* FSQ106
* SBIG STF8300F at -15 degC

Total integration time: (8*5 min + 10*10 min) = 2 hours 20 min.

I can supply other info if you like.

cytan

[Rkonrad]

Cytan

Thanks for the spec of your equipment
I got distracted by my processing and forgot about the cyan stars:)

Have you tried selecting the stars for sampling in the colour module? I think I tried this but wasn't happy with the galaxy colour. I'll post the log in a day or so.

Cheers Richard

[Rkonrad]

Hi Cytan,

Attached is the log file for one of the processing attempts I used. I'm afraid I'm sure which one was more successful - nevertheless my steps are similar. There's a lot of data in the log file so I isolated it.

Cheers Richard

File loaded [/home/rkonrad/Downloads/startools-example/more/cropped_M31.fit].
---
--- Crop
Parameter [X1] set to [15 pixels]
Parameter [Y1] set to [23 pixels]
Parameter [X2] set to [1611 pixels (-16)]
Parameter [Y2] set to [1219 pixels (-25)]
--- 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 [6 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [75 %]
--- 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 [6 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 [20 %]
--- HDR
Parameter [Small Detail Precision] set to [Max]
Parameter [Channels] set to [Brightness Only]
Parameter [Algorithm] set to [Equalize]
Parameter [Dark/Bright Response] set to [0.14]
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 [Yes]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [3 pixels]
Parameter [Aggressiveness] set to [59 %]
Parameter [Dark Anomaly Headroom] set to [15 %]
Undo.
--- HDR
Parameter [Small Detail Precision] set to [Max]
Parameter [Channels] set to [Brightness Only]
Parameter [Algorithm] set to [Reveal DSO Core]
Parameter [Dark/Bright Response] set to [4.92]
Parameter [Detail Size Range] set to [537 pixels]
Parameter [Strength] set to [1.4]
--- Contrast
Parameter [Expose Dark Areas] set to [No]
Parameter [Compensate Gamma] set to [Yes]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [3 pixels]
Parameter [Aggressiveness] set to [58 %]
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 [3.1 pixels]
Parameter [Amount] set to [66 %]
Parameter [Small Detail Bias] set to [75 %]
--- 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 [0 %]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [100 %]
Parameter [Strength] set to [55 %]
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 [1.00]
Parameter [Green Bias Reduce] set to [1.17]
Parameter [Red Bias Reduce] set to [1.15]
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 [4]
Parameter [Color Detail Loss] set to [12 %]
Parameter [Brightness Detail Loss] set to [12 %]
Parameter [Grain Size] set to [3.2 pixels]
Parameter [Read Noise Compensation] set to [Off]
Parameter [Smoothness] set to [78 %]
File saved [/home/rkonrad/Downloads/startools-example/more/cropped_M31.tiff].
Undo.
--- 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 [1.00]
Parameter [Green Bias Reduce] set to [1.21]
Parameter [Red Bias Reduce] set to [1.17]
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 [6]
Parameter [Color Detail Loss] set to [13 %]
Parameter [Brightness Detail Loss] set to [13 %]
Parameter [Grain Size] set to [7.4 pixels]
Parameter [Read Noise Compensation] set to [Off]
Parameter [Smoothness] set to [76 %]
--- 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 [9.90]
Parameter [Bright Saturation] set to [9.90]
Parameter [Saturation Amount] set to [100 %]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.03]
Parameter [Red Bias Reduce] set to [1.00]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.00]
Parameter [Skyglow] set to [2 %]
Parameter [Digital Development] set to [Off]
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]
File saved [/home/rkonrad/Downloads/startools-example/more/m31.tiff].
--- 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 [Full]
Parameter [Bright Saturation] set to [9.80]
Parameter [Saturation Amount] set to [112 %]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.00]
Parameter [Red Bias Reduce] set to [1.00]
Parameter [Mask Fuzz] set to [1.0 pixels]
File saved [/home/rkonrad/Downloads/startools-example/more/m31.tiff].
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [0.96]
Parameter [Skyglow] set to [2 %]
Parameter [Digital Development] set to [Off]
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]

[cytan299]

Hi Richard,
Thanks!

cytan