DSS Settings for StarTools

Questions and answers about processing in StarTools and how to accomplish certain tasks.

DSS Settings for StarTools

Postby Guy » Tue Feb 24, 2015 11:07 am

Hi,

I'm new to Astrophotography and I am having a bit of trouble processing an image in Startools. I am doing the stacking in DSS and I know some settings affect StarTools' ability to process the image. As a first step I wanted to check that I had correctly set all the options in DSS that affected Startools processing.

From reading this forum and others the main settings I have are:

Stacking Parameters:
  • Light Tab: Mode: Kappa Sigma Clipping with Kappa of 2 & 5 iterations
    and Select 'No Background Calibration' option
  • Dark Tab: Mode: Median combination
    and Check 'Hot Pixel detection and removal' and uncheck 'Dark Optimisation'
  • Cosmetic Tab: Uncheck 'Detect and clean remaining hot pixels'
    and uncheck 'Detect and clean remaining cold pixels'
  • Result Tab: Uncheck 'Align RGB Channels in Final Image
RAW/FITS DDP Settings:
  • Raw Files Tab - Uncheck 'Use Auto White Balance' and uncheck 'Use Camera White Balance'
  • Bayer Matrix Transformation: select 'Bilinear Interpolation' option
There are other options set which I think do not affect Startools processing such as:

Register Settings:
  • Advanced Tab: Check 'Reduce the Noise by using a median filter'
Stacking Parameters:
  • Stacking Mode: Median Kappa Sigma Clipping with Kappa of 2 & 5 iterations
  • Intermediate Files tab: Final Image File Format: TIFF or FITS
I understand that DSS applies the white balance even if told not to
- so I need to use option 1 'Linear, was not Bayered or is whitebalanced' when opening the file in StarTools.

Are these settings correct and do you know of any other settings that are important?

Thanks,
Guy
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Re: DSS Settings for StarTools

Postby admin » Tue Feb 24, 2015 9:48 pm

Guy wrote:Hi,

I'm new to Astrophotography and I am having a bit of trouble processing an image in Startools. I am doing the stacking in DSS and I know some settings affect StarTools' ability to process the image. As a first step I wanted to check that I had correctly set all the options in DSS that affected Startools processing.

From reading this forum and others the main settings I have are:

Stacking Parameters:
  • Light Tab: Mode: Kappa Sigma Clipping with Kappa of 2 & 5 iterations
    and Select 'No Background Calibration' option
  • Dark Tab: Mode: Median combination
    and Check 'Hot Pixel detection and removal' and uncheck 'Dark Optimisation'
  • Cosmetic Tab: Uncheck 'Detect and clean remaining hot pixels'
    and uncheck 'Detect and clean remaining cold pixels'
  • Result Tab: Uncheck 'Align RGB Channels in Final Image
RAW/FITS DDP Settings:
  • Raw Files Tab - Uncheck 'Use Auto White Balance' and uncheck 'Use Camera White Balance'
  • Bayer Matrix Transformation: select 'Bilinear Interpolation' option
There are other options set which I think do not affect Startools processing such as:

Register Settings:
  • Advanced Tab: Check 'Reduce the Noise by using a median filter'
Stacking Parameters:
  • Stacking Mode: Median Kappa Sigma Clipping with Kappa of 2 & 5 iterations
  • Intermediate Files tab: Final Image File Format: TIFF or FITS
I understand that DSS applies the white balance even if told not to
- so I need to use option 1 'Linear, was not Bayered or is whitebalanced' when opening the file in StarTools.

Are these settings correct and do you know of any other settings that are important?

Thanks,
Guy


That sounds good!

A very important one is this though;

Screenshot-Stacking Steps-2.png
Screenshot-Stacking Steps-2.png (40.21 KiB) Viewed 2743 times
(e.g. the calibration options set to 'no')

Looking forward to your results!
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Re: DSS Settings for StarTools

Postby Amaranthus » Wed Mar 04, 2015 2:01 am

If you pre-convert your RAW files into TIFF using dcraw, you can avoid problems with white balance etc. This is what I do when using my DSLR.
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Re: DSS Settings for StarTools

Postby Guy » Wed Mar 04, 2015 9:38 am

Thanks for your responses.

I was imaging the Rosette nebula using an unmodified Canon 1000D - getting 20 5-minute subs.

I've stacked the Lights, Darks, Flats and Bias frames using the settings above and got the following image:
https://app.box.com/s/x9xhneyv3417n4h8ib4yi58425trvtf3

I processed it using StarTools and got the image below:
https://app.box.com/s/nd8dw22452j8jesshydlz2x9virff9de

My questions about it was:
- I needed to increase the saturation a great deal to bring out any colour - is this normal?
- There is a lot more blue than other images I've seen - is this just because the camera is unmodified or am I processing it wrong?
- This is my first guided image and one of the first I have processed using StarTools - is there any other advice regarding processing you can give?

Any advice would be welcome.
Guy
 
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Re: DSS Settings for StarTools

Postby admin » Thu Mar 05, 2015 4:42 am

That is a truly excellent result, showing very good coloring, and I'll tell you why;

  • The full (visible) black body radiation spectrum is covered; your image shows red, orange, yellow, white and blue stars.
  • Your diffraction pattern shows a nice 'rainbow' of different colors.
  • The red H-alpha, mixed with blue from Hb (sometimes OIII) yields the signature red/purple of a HII region (as seen in the outer regions of your image). The hot O-type stars are responsible for exciting the hydrogen and the emissions.
  • The blue in the centre is reflection of the hot, bright, blue O-type stars in that area - much of the lighter gas has been blown away by the extreme stellar winds.

StarTools takes coloring very seriously, trying to maintain informative coloring like this throughout the image. (see here for more info about why this important)

As for your question about Saturation;
I strongly suspect it may also have something to do with the screen-filling nebulosity and having no real background to calibrate against for Wipe to do its job. This will see Wipe calibrating a lot of nebulosity to to 'neutral'. You could lower the Aggressiveness parameter by quite a bit to make Wipe look much further for background to calibrate against than just locally. Doing this, Wipe wil be more generous ('less aggressive') with retaining background color and you will need to push saturation a lot less.

Have you tried using the Lens module? It can help alleviate the coma somewhat. You may also want to consider dithering between frames, as I can see some pattern noise. The data is quite nice and clean otherwise!

Love this image! :thumbsup:
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Re: DSS Settings for StarTools

Postby Guy » Thu Mar 05, 2015 8:51 am

Thanks for the explanation and kind words about the image. If the colours are good its thanks to StarTools (and the Canon !). I've enjoyed using StarTools. Even with my limited experience I can use its' powerful tools easily.

I had read about the Scientific approach to handling colour and so I was thinking that there may be some difference from other images of the Rosette - which are often shades of red - but I hadn't expected such a difference. There are also many blue stars which made me think I might have done something to emphasise the blue. Good to hear I haven't.

I did reduce the aggressiveness a bit when using Wipe but I will see what a effect further reduction has.
I haven't tried using the Lens module to tackle the coma - I think I used the Repair module on this version so I'll give the Lens module a go.
I'll also try dithering between frames.

Thanks once again.
Guy
 
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