Shrink Module Use (v1.7)

Notes from users, documentation addendums.
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Shrink Module Use (v1.7)

Post by Guy »

Here are some notes relating to using this module. It is not the only way to use the module and experimentation is encouraged.
Please let me know if anyone sees any errors or has any additional advice they think helpful.
I will update this post as needed.
To see a full alphabetical list of module topics click here

Shrink Module (v1.7.420+)

  • To modify the way stars look in the image - by shrinking bloated stars, recover the colour and manipulate the core and halo.
For a general overview see Shrink: Star Appearance Manipulation
This module can be used to control bloated stars (with the Tighten algorithm) that the Decon module had trouble with - possibly because they were overexposed. It changes the star sizes. It complements the Repair module which is used for severely deformed stars.

Useful Sources

The notes below relate to StarTools version 1.7.420+.

When to use:
  • After the Color module but before Tracking is turned off.
  • Be careful when shrinking stars on widefield images. There is often not much background for the algorithm to draw from.
  • Can be used more than once.
Example Workflow (v1.7):
AutoDev-{Lens}-Bin-Crop-Wipe-AutoDev (or FilmDev)-{Contrast/HDR/Sharp/Decon/Flux}-Color-{Shrink/Filter/Entropy/SuperStr}-Track/NR-{Layer/Heal/Repair/Synth/Stereo 3D}
Key: {...} optional modules

Example Workflow (v1.8):
{Compose}-AutoDev-{Lens}-Bin-Crop-Wipe-AutoDev (or FilmDev)-{Contrast/HDR/Sharp/SVDecon}-Color-{Shrink/Filter/Entropy/SuperStr/NBAccent/}-Track/NR(Unified-Denoise)-{Flux/Repair/Heal/Layer/Synth}
Key: {...} optional modules

To shrink and improve the colour in stars.
  1. When prompted for Star Mask, click Auto-generate mask.
  2. Set Mode to Tighten - This mode will shrink any overexposed parts of your stars and draw any colored part into the core.
  3. Set Iterations to whatever you like (more iterations draws color in further).
  4. 'Keep' the result.
What result to look for:
If the Mode is set to Tighten
  • Stars are more concentrated and have improved colour.
  • Check for any halos being introduced - try reducing Color Taming if so.
  • Check for any ringing. This can be increased by Shrink. Try increasing the De-ringing parameter.
After Use:
  • Consider using other modules that support Tracking before turning Tracking off - like Super Structure
Special Techniques:

Alternative way to Repair Stars with Halos:
  • Mask the stars and their halos.
  • Load Shrink module
  • Set Iterations to 0 (no shrinking)
  • Set De-ringing Off
  • Increase the Color Taming parameter as needed - the stars will take on some colour from their surrundings
  • Keep
Description of Controls:

For general instructions on using masks see Mask
  • The use of a star mask is highly recommended.
  • The Auto-generated star mask should catch all major stars but leave the smaller ones.
  • You may want to exclude areas from being affected by Shrink - or to be less affected by using a less aggressive mask in places.
  • To select other stars as well you can run the mask module more than once by setting 'Old Mask' to 'Add New to Old' - see 'Creating a suitable mask' here
  • Tighten - Sets Mode to Tighten, Iterations to 10
  • Dim - Sets Mode to Dim, Iterations to 10, Halo extend to 2 pixels
  • Classic - Mimics 'Shrink' mode behaviour of old Magic module. Sets Mode to Dim, Iterations to 1, Deringing to Off, Color taming to 0 pixels, Regularisation to 0.00.
  • Un-glow (v1.7.443+) - Sets Un-glow Strength to 35% and Un-glow Kernel to 30.0 pixels
Defines the Mode the Shrink module operates in:
  • Dim - Dims the stars luminosity.
  • Tighten - Reduces the star halos, drawing them in to the star. Does not affect the star core.
Sets the number of times the shrink algorithm is run.
  • The greater the number of iterations the stronger the effect selected by the Mode setting.
  • Default is 10. Range is 0 to 30.
This settings helps control any ringing artefacts that may occur if the image was previously deconvolved or sharpened.
  • Increase this value if there are issues related to ringing artefacts.
  • Default is 1.5 pixels. Range is 1.0[Off] to 10.0 pixels.
Color Taming:
This setting controls how the star progressively takes on the colour of the surroundings.
  • Default is 2 pixels. Range is 0 to 40 pixels.
This controls how much each iteration of the process is dampened by. This is used to avoid pitting or stringing artefacts.
  • Reduce this setting if any pitting or stringing artefacts appear around stars.
  • Default is 0.85. Range is 0.00 to 1.00.
Halo Extend:
Has the effect of temporarily growing the selected mask - so including more of the stars surroundings.
  • Default is 1 pixel. Range is 0 to 10 pixels.
Un-glow Strength (v1.7.443+):
Un-glow attempts to reduce the halos around bright stars. This parameter controls the strength of that effect.
  • Default is Off. Range is 0[Off] to 100%.
Un-glow Kernel (v1.7.443+):
This defines the width of the halos that the Un-glow feature should detect and control.
  • Default is Off. Range is 1[Off] to 30.0 pixels.
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