Synthesise New Blue Green ( Cyan ) Data Set

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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Startrek
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Synthesise New Blue Green ( Cyan ) Data Set

Post by Startrek »

Ivo,
I’ve synthesised a synthetic luminance data set as per your advice in IIS, red , green and blue with double exposure time for green etc.........and processed in mono until the colour module
But I’m having trouble understanding your procedure for synthesising a green blue ( Cyan) data set
Could you run through a procedure with a bit more operational detail for the synthesised blue green Data set and how to import it etc.......,
Remember I’m running version 1.5
Thanks in advance
Martin
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by admin »

Hi Martin,

To synthesise a new channel from green+blue (constituting O-III), it's probably easiest to use the Compose module;
  • Load your OSC/DSLR dataset as blue (blue data is automatically extracted)
  • Also load your OSC/DSLR dataset as green (green data is automatically extracted)
  • Set "Luminance, Color" to "L + Synthetic L from RGB, Mono"; this will be your new blue+green ("cyan") dataset.
  • Save this dataset.
  • You can now re-import this into the Compose module into the blue and green channels for the purpose of colouring.
Does that help?
Ivo Jager
StarTools creator and astronomy enthusiast
Startrek
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Joined: Mon Dec 30, 2019 3:49 am

Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by Startrek »

Ivo
Thanks
Got it !
Martin
Startrek
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by Startrek »

Ivo
I’ve just downloaded V1.6 but yet to look at it especially the compose colour options
How important is exact exposure times when loading your Lum, R, G, B data sets
The default is 1 hr 3600 sec , so hypothetically if I captured 2 hrs on M8 with my new OSC ZWOASI2600MC camera , what would you recommend the balance of exposure times should be for Lum , R, G, B if I’m going to process straight LRGB images vs Other types
Hope the above makes sense
Thanks in advance
Startrek (Martin)
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by admin »

Startrek wrote: Mon Sep 07, 2020 2:13 am Ivo
I’ve just downloaded V1.6 but yet to look at it especially the compose colour options
How important is exact exposure times when loading your Lum, R, G, B data sets
The default is 1 hr 3600 sec , so hypothetically if I captured 2 hrs on M8 with my new OSC ZWOASI2600MC camera , what would you recommend the balance of exposure times should be for Lum , R, G, B if I’m going to process straight LRGB images vs Other types
Hope the above makes sense
Thanks in advance
Startrek (Martin)
Thanks Martin. Can you you clarify for me whether you shot Lum, R, G and B separately with your OSC? (and if so, why?)
Cheers!
Ivo Jager
StarTools creator and astronomy enthusiast
Startrek
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by Startrek »

Ivo
No I didn’t image separately
When in LP Sydney I use my ZWO 2” Duoband filter and try to capture 20% more data than my dark site south coast NSW
Cheers
Martin
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by admin »

Startrek wrote: Mon Sep 07, 2020 3:22 am Ivo
No I didn’t image separately
When in LP Sydney I use my ZWO 2” Duoband filter and try to capture 20% more data than my dark site south coast NSW
Cheers
Martin
Ok, then, assuming you have just a "regular" single dataset (e.g. in color with 3 separate channels), you will want to do the following in 1.6 (not that 1.7 alpha has dedicated Luminance, Color settings for your particular use case);

Leave Luminance, Color at "L + Synthetic L from RGB, RGB". Then, load the same dataset for R, for G and for B.
Double the exposure time for G of whatever you choose for R and B.

Explanation; the actual exposure times are not important - it's the 2:1 ratio that is important here. You OSC's Bayer matrix has 2x more green green samples than red or blue samples. Doubling the exposure time of the green channel takes this into account. The exposure times/ratios are then used to create synthetic luminance (in your case with green weighted higher), which you will go on to process as your detail. A bog standard colour dataset will be created from R, G and B without any special reweighing.

Once you hit the Color module, however, the Matrix parameter will allow you to manipulate the allocation/blending of R, G and B (without impact the detail you just processed at all!). For example you could choose the "HOO Duoband 100R, 50G+50B, 50G+50B" option (as chosen by the Bi-Color preset) for that popular red/cyan bi-colour look. Or some entirely different colour scheme - it's up to you!

Hope this helps!
Ivo Jager
StarTools creator and astronomy enthusiast
Startrek
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Re: Synthesise New Blue Green ( Cyan ) Data Set

Post by Startrek »

Ivo
Thanks for the detail , exactly what I was after
Cheers
Martin
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