Workflow tutorial: using SIRIL 1.4 including GraXpert, Cosmic Clarity Suite Pro and Veralux python scripts

  Blogger isn't always the most intuitive platform to navigate - but it is free and simple to use and manage. 

To help you find information quickly on this blog, you can

• use the search bar using key words e.g. Asiair mini
• use the blog menu list by date 
• use this page which will be regularly updated https://undersouthwestskies.blogspot.com/2025/12/want-to-find-something-quickly-on-my.html

Updates January 2026

The rapid development of Veralux Python scripts has been breathtaking this month. As a result I am adding some updates to this page. These can be found at the bottom of this original post - as a postscript. Any future updates will appear in the same place. 

This post was published 13.12.25

Optimal workflow using SIRIL with COSMIC CLARITY SUITE PRO, GRAXPERT and AFFINITY PHOTO

I have written a previous post about my SIRIL workflow which you can find here  https://undersouthwestskies.blogspot.com/2025/01/a-beginners-guide-to-using-siril-some.html

This post was updated early December 2025, late December 2025. 

In this post I 

·       share my more simplified, reorganised workflow - which is based on SIRIL vs 1.4, and the python scripts for Cosmic Clarity Suite (by Seti Astro), Veralux and GraXpert. 

·       Try to give notes and tips which will help beginners

·       Share some useful, helpful YouTube tutorials

So, let’s get stuck straight in to my latest workflow: PLEASE NOTE - screenshots will be added when I process my next image - so please bear with me until then 

NOTE: I am assuming you have a little knowledge of how to organise your images – if you are going to be using SIRIL – if you are new to SIRIL the jump down to the bottom to watch one or two of the videos first.

Below is a simple graphic image which simplifies my workflow approach: 

and here is a simple infographic I tried to design based on SIRIL and not using the latest cosmic clarity and veralux python scripts 

A.      Organisation:

1.      Organise your folders into one folder called SIRIL and then sub folders for – lights, biases, darks and flats

2.      Set your home directory top menu bar left hand side

3.      Choose scripts – siril script files  - OSC pre-processing.ssf  to start the stacking process

 

B.      Crop and gradient removal:

1.      Be in autostretch mode on bottom task bar

2.      Load results.fits file produced from your stacking script – find in your home directory

3.      Crop edges to remove stacking artefacts

4.      Tools – astrometry  - image plate solver  on the pop up window:

a.      In pop up window - search catalogue number; (S box = if southern hemisphere image); click metadata from image; check – siril solver, solution order – cubic, flip image, auto-crop for wide field, star catalogue auto, catalogue limit – auto.

5.      Background extraction – image processing – python scripts - AutoBGe seti

a.      use default settings in the pop up window initially i.e. sample points 100, polynominal 2 RBF smoothness – 0.1.  (L-Enhance note - Use degree 2 to avoid flattening extended Ha regions).

b.      On the pop up window – can opt to click add exclusion area – (this is what you don’t want extracted) – free hand draw in around nebula area to be excluded – if make a mistake – click clear selection and start again – then when ready click process

c.      Use undo/redo arrows to compare before and after to see the changes

NOTES: background extraction

1.      Can use GraXpert for BGE  – GraXpert uses AI model - don’t do denoise now just BGE – severe gradients <0.5; mild gradients >0.5

6.      If using SIRIL BGE – grid tolerance 3, squares off nebula and bright stars; click dither to on; subtraction on; polynominal – increase for very bad gradients – RBF tab – smoothing default 0.5

 

C.     Colour calibration:

1.      NOTE – must have done image plate solver before doing colour calibration

2.      Autostretch mode on lower menu bar

3.      Remove chromatic aberration – python script - aberration remover – can do now or after colour calibration – either

4.      Plate solve image – if not already done above MUST DO BEFORE COLOUR CALLIBRATION WORK  - needs internet connection - astrometry - image plate solve

5.      Colour calibration – image processing tab – colour calibration - Spectrophotometric colour calibration

a.      SPCC – needs internet – tick the following: average spiral galaxy, one shot colour, osc sensor – closest, osc filter – optolong L pro OR if narrow band – check narrow band box and enter your filter details ( L enhance details for table – see below; tick background reference to auto detection.

b.      Settings if using L-enHance filter - – wavelength : blue OIII – 500; Green HB – 486; red H-alpha 656.3 and BW – OIII green 24; red 10; Blue 24

 

D.     Cosmic clarity sharpening  before denoise

a.       DO BEFORE STRETCHING I.E. LINEAR DATA

                                                  i.      stellar = stars only; non stellar = background and other objects - do both stellar and non stellar on pop up window OR experiment using undo/redo arrows – use GPU, clear input directory, (stellar sharpening  - 0.5 default and play with slider; or move first slider to 0.20 to 0.25; non stellar slider to 0.80; non stellar strength to 3. Zoom in a check – use undo and redo buttons to see differences made

b.      OPTIONAL – could do DENOISE now – scripts – python scripts - CC denoise – use RGB channel; check GPU and Clear input directory.     ** New veralux silentium python script is also a denoise option - must be done on linear images i.e. before image is stretched. To get this new script - go to scripts tab and get scripts and then go down the list - select the veralux script bar and check the box at the end. NOTE: as of late december 2025 - note that under scriupts tab - veralux now has its onw heading

c.      Now find output folder in Cosmic Clarity home folder on C drive and delete files as you go.

** If you use the new veralux silentium denoise script - I tend to use the default settings. when the preview box appears - it shows the settings in effect. To see the original image just press and hold down the space bar. the red box on the preview screen can also be moved about and acts as a zoom in function - so drag and drop it to the area you want to focus on. 

E   OPTIONAL stretching now – using Veralux hypermetric Stretching  NOTE – SEE F BELOW BEFORE DECIDING

a.      MUST DO PLATE SOLVING AND SPCC COLOUR BEFORE HAND

b.      Linear view – then Scripts – python scripts – processing – Veralux hypermetric stretching

c.      Settings for pop-up window:

a.      Processing – ready to use

b.      Sensor calibration – top one or canon 600d or 709re recommended.

c.      Click live view – use mouse scroll wheel to zoom in and out

d.      Target background – start 0.10 (0.2 is default) (lower the number the more contrast and darker the image – higher the number the less contrast and brighter the image)

e.      Log D – strength of stretch – leave at default 2.00

f.        Click auto calculate

g.       Protect B – how protected stars are during stretch – leave on default

h.      Star core recovery – leave default 3.5

i.        Process

j.        Make adjustments and experiment with setting inputs until happy

k.       If over saturated use the slider – but RECOMMENDATION IS DON’T TOUCH THE SLIDER – chromatic preservation colour one  - after alteration click auto calculate again

l.        Can also now apply curves transformation if image looking too washed out etc – or wait until starnet

d.      If choose scientific – then after do series of transform curve stretches in siril to bring up contrast and colour – s curves to raise darks, MT and HL’s

F. Star removal: I always DO BEFORE STRETCHING so I'd do section E above AFTER doing the starnet separation

1.      Optional first step: Image processing – star  processing desaturate stars

2.      Image processing – star processing - Starnet – tick prestretch in pop up window

3.      Stretching starless nebula – keep linear below in bottom menu

a.      OPTIONS: either Veralux hypermetric stretch as above OR Cosmic Clarity statistical stretch – see below

                                                  i.      Statistical stretch – in linear mode - target median 0.11 for anything not filling entire frame; normalise- no curves adjustment; if fully fills frame target median at 0.25 starter.

                                                 ii.      Stretch until: - Nebula structure is visible      Background is not clipped   Stars not blown out – NB if done colour correction already must check linked stretch box.
Now the image is nonlinear and ready for detail work.

b.      NOTE – CAN STILL DO OLD WAY IF DESIRE – SEE BELOW:

                                                  i.      OR – asinh stretch first followed by HTF stretch –  (HTF stretch using lhs and middle triangles or placing points on curve line to get shallow s curve  - watch clipping % - ensure no clipping of data –  ( can use ROI – draw box on part of nebula – right click select |ROI – select ‘set to selection’ and do adjustments; to remove – go back to menu and click ‘clear ROI’

                                                 ii.      OR Can also retry with curves adjustment ticked – try boost slider at 0.5 – the greater the boost the more contrast and fainter detail at expense of more noise and artefacts - 

                                               iii.      OR can do curves transformation – tiny iterative changes and repeat image processing – stretches – curves transformation – click on line and drag up or down – aim shallow s curve – don’t clip data – make very small adjustments – repeat gently LESS is MORE 

EXPERIMENT WITH EACH UNTIL HAPPY – use undo/redo arrows

4.      Complete denoise now – scripts – python scripts – processing – cosmic clarity denoise Denoise

a.      In pop up windopw - full strength – do zoom in and undo/redo to check difference

b.      alternative is denoise in siril  - if using GRaXpert – default stretch 0.5 so try 0.8

 

(NOTE – could try  SETI ENHANCER if you have it downloaded — Star Control, Detail Boost, Color Punch at this stage -
Load the denoised stretched image into SETI Enhancer.

·        Star Reduction - Use after stretch, not before.   Strength: 10–30%    Helps separate the nebula from crowded star fields      Avoid “donut-shaped” stars—dial back if seen

·        Nebula Detail Enhancement   Use:   Local contrast      Midtone sharpening    Texture boost
Moderate levels keep it natural.

·        Color Enhancement
Increase nebula saturation       Adjust hue sliders for Ha/OIII separation      Use vibrance before saturation
Avoid boosting star colours too strongly

·        Background Balancing
Use background equalizer if available     Ensure background is smooth and neutral
Remove remaining gradients)

G. Process starmask:

1.      Could Desaturate stars now – see above where outlined previously

2.      Can do Asinh stretch or  htf stretch – keep mild – use square and eyedropper Asinh Stretch:  Broadband: 5–15 L-Enhance: 3–8    Black point: 0.001–0.003   

3.      If doing GHS: Stretch: 0.8–1.2     Midtones:  Broadband: 0.3–0.5  L-Enhance: 0.2–0.35

Stop here.  Do not adjust saturation, HDR, clarity, sharpening. OR

4.      Could Reduce star size now – image processing - morphological transformation – selection – strength 5 – 20%

5.      Optional Slight saturation boost  - image processing – colour saturation: do globally

H. Star re-composition:

1.      Image processing – star processing – star re-composition

2.      On pop up histograms - RHS is starmask; LHS is starless

3.      Do black point adjustment to starmask to reduce number of stars

4.      Adjust blend to avoid halos and bright stars – inspect fine details – zoom to check edges

5.      Final noise reduction – optional light GraXpert or cc denoise – avoid over-smoothing background or killing faint dust

Final tweaks:

1.      Vibrance, colour balance

2.      Final cropping/rotation  to choice

3.      Green noise check – SCNR (Green Noise Removal) – BEST = SIRIL   Broadband: Strength: 0.60–0.75  L-Enhance:  Use none or mild (0.20–0.35)      OIII contains green, so don't destroy it.

4.      Export 16 bit TIFF

PS Videos that I found useful: 

Look for AstroIslander's part 2 and 3 as well 

Updates January 2026

The rapid development of Veralux Python scripts has been breathtaking this month. As a result I am adding some updates to this page: 

1. Here is a revised work flow that I have been using, based almost entirely on the Veralux suite in SIRIL. It is mainly 'narrowband imaging' orientated. 

2. NARROWBAND WORKFLOW USING VERALUX SCRIPTS

This is a new work flow I am trying after using my Optolong L-enHance filter

BASIC WORK FLOW ORDER:

•      Crop
•      Plate solver 
•      Scripts - siril scripts - AutoBge 
•      scripts - siril scripts - CC sharpening 
•      Starnet removal - tick pre-stretch box
•      On starless image in linear mode - run Veralux Alchemy (see notes below) 
•      Complete Veralux Hypermetric Stretch and possible follow up > image processing - stretches - curves transformation to brings darks down slightly and brighten slightly highlights ) shallow 'S' curve) 
•       SAVE image
•       OPTIONAL: Image processing – filters – CLAHE (toggle preview on/off; play about with slides) SAVE
•       Veralux star recomposer – load RGBstars; load veralux alchemy linear fit file
•       Python scripts – processing – HDR multiscale
•       Veralux Vectra colour grading
•       Possible final image processing - stretches - curves transformation
•       Finishing in Affinity Photo 

3. Some notes about Veralux Alchemy

 Alchemy is for use when narrowband imaging. It leads to proper channel normalization, mixing without destroying colour integrity and structure.            

Useful if you are using one shot colour camera and optolong L-enHance

DON’T DO COLOUR CALIBRATION BEFORE USING ALCHEMY SCRIPT

LINEAR ONLY – MUST BE USED BEFORE STRETCHING DATA

ALCHEMY

·          Select sensor or OSC preprocessing

·       Enable Quantum On Mixing box

·       Normalisation – enable BG neutralization; enable Auto signal Fit

·       OIII – boosts blue (double click slider returns to default)

Palette Mixer

·       Default grey box setting = HOO

·       Sliders do the blends – so note the %’s

·       Pseudo HOO – changes slider %’s (50% green)

·       HSO preset = 100% OIII

SELECT YOUR PRESET then play with normalization OIII  slider

4. Veralux Vectra notes 

Perceptual colour grading with LCH (Lightness, chroma, Hue) for final astrophotography polish

VECTRA is a final step tool  - smoother colour transitions, refined saturation, balanced tonal

MUST BE USED ON IMAGE THAT HAS BEEN STRETCHED

Use either at end of work flow OR before star recomposer

VECTRA

•       Two tabs – primary (RGB) and secondary (YCM)
•       Sliders for each – can shift hue and/or saturation
•       Enable vector scope box – watch vector scope when using slider as well as image change
•       Know which areas of image want to enhance in advance of use
•       Same for using saturation sliders
•       AIM: to do final colour work on image
•       Shadow authority slider – prevents background changes – most of time sits far LHS – can affect colour of image target – so use very tiny steps  - keep watching for background changes
•       Enable white star integrity on images with stars – disable on starless images 

5. Veralux Star Recomposer notes 

Adds stars back into starless image after Starnett++ removal – replaces star recomposition

1.       In pop-up window load starmask and load starless image

2.       Linear for most images except galaxies

3.       Sensor profile – canon EOS modern

4.       Use star intensity slider

5.       Profile hardness = stars pinpoint level – default = 6

6.       Colour physics = star colour intensity

7.       Advanced tab –

a.       Core – removes artifacts around stars

b.       Reduction – reduces star size

c.       Optical healing – reduces halos around stars to improve colour