Shrink (Magic) Module Use (v1.5-v1.7-)

Notes from users, documentation addendums.
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Shrink (Magic) Module Use (v1.5-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 (aka Magic) Module

  • 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 Magic: Star Appearance Manipulation
This module can be used to control bloated stars (with the Shrink or 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
There are a number of useful links in StarTools Links and Tutorials.

The notes below relate to StarTools version 1.5, 1.6, and 1.7 up to 1.7.419.

When to use:
  • Can only be used when Tracking is off. Towards the end of the processing workflow.
  • Can be used more than once.
Example Workflow:
AutoDev-{Band/Lens}-Bin-Crop-Wipe-AutoDev(or Develop)-{As needed: Decon/Sharp/Contrast/HDR/Flux/Life}-Color-{Filter}-Denoise-{If needed: Layer/Shrink/Heal/Repair/Synth}
Key: {...} optional modules

To shrink and improve the colour in stars.
  1. Create Star Mask.
  2. Set Mode to Shrink Core - 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. You might also want to increase the 'grow mask' parameter 1 or 2 pixels.
  5. 'Keep' the result.
  6. Launch the Color module.
  7. Bump up the Saturation parameter to accentuate the star colour.
  8. 'Keep' the result.
What result to look for:
If the Mode is set to Shrink or Tighten
  • Stars are more concentrated and have improved colour.
After Use:
  • Consider using other modules that require Tracking to be off - like Heal, Repair and Synth.
Special Techniques:

Reduce bloom around bright stars
This is a way of using the module to reduce the halo or bloom around bright stars:
  1. Create Star Mask.
    • Open Mask editor and click Auto - Stars
    • Set Selection Mode to 'Highlights>Threshold'
    • Set Threshold to about 90% - depending on the brightness of the stars you want to include.
    • Click 'Do' - The star cores will be selected (green).
    • Click Grow as needed to expand to cover the whole star.
    • Keep the result when done.
  2. Set Mode to 'Tighten' - This mode will remove the halo that is around the star (as long as it is within the mask).
  3. Set Iterations to whatever you like (more iterations draws color in further).
  4. You might also want to increase the 'grow mask' parameter 1 or 2 pixels if not all the halo is selected.
  5. 'Keep' the result.
Description of Controls:

For general instructions on using masks see Mask
  • The use of a star mask is highly recommended.
Defines the Mode the Magic module operates in:
  • Shrink - Shrinks the full star. It is best applied when star fields in wide-field images detract from a DSO. It is also useful to subtly make blown out stars appear less blown out.
  • Shrink Core - Shrinks only the star core, gradually filling the core with pixels that are not completely white.
    • Draws color into a star's core by progressively adopting surrounding pixels for the overexposed core - Bringing the stars colour into the core.
    • It may also help to subsequently increase the stars colour using the Color module.
  • Expand Core - Expands the star's core.
  • Tighten - Reduces the star halos, drawing them in to the star. Does not affect the star core.
Sets the strength of the effect.
  • Default is 1 pixel. Range is 0 to 30 pixels.
Mask Grow
Sets the amount to temporarily grow the mask by. Use this if rings occur in or around the stars when using a star mask.
  • Default is 1 pixel. Range is 0 to 10 pixels.
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