Entropy Module Use

Notes from users, documentation addendums.
Post Reply
Posts: 158
Joined: Thu Feb 19, 2015 8:35 am

Entropy Module Use

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.
For an index of similar notes on the other StarTools modules see StarTools Main Window Use.

Entropy Module

  • To enhance the local detail in the image - using information in the colour within your data. Works with both narrowband and broadband data.
For a general overview see Entropy: Inter-channel Entropy-driven Detail Enhancement
It uses the idea that interesting features have distinct colours - derived from the emission lines of what they are made of, or the light they reflect.
This idea can be well exploited when using narrowband data where each channel represents a different part of the spectrum.
The module identifies local detail in each band and locally adjusts the weighting of the bands luminance contribution to highlight the detail.
By default the Entropy module works on all bands and darkens and brightens to bring out the detail evenly.
With Tracking on, noise will be tracked and taken care of when Denoise is done when Tracking is switched off.
With Tracking off, noise reduction is applied within the module itself.

Useful Sources
There are a number of useful links in StarTools Links and Tutorials.
There is a good general description of the Entropy module here
There is also a YouTube video: introducing the new Entropy module.

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

When to use:
  • When you want to improve the detail in the image - and highlight the changes in colour.
  • When the object fills much of the image.
  • Very effective with narrowband data - also works with broadband data from OSC and DSLR cameras.
  • Use after using the Color module. The Entropy module will be greyed out until the Color module has been applied.
  • With Tracking on, prior colour balancing does not affect the result.
  • Works on both unstretched and stretched data (e.g. .JPG data)
Example Workflow (v1.7):
{Compose}-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/Stereo 3D}
Key: {...} optional modules

This is a way of using the module which should give good results in most cases:
  1. Load the module.
  2. Adjust the Resolution as needed.
  3. Press 'Do' to generate the entropy map and get initial results.
  4. Try different settings of Strength, Dark/Light Enhance, and Midtone Pull Filter and Strength until you get the right effect.
  5. Press 'Do' to update to see the results of the changed settings.
  6. Press 'Keep' when you have the results you prefer.
What result to look for:
  • Increased detail in the image where the colour changes.
After Use:
  • You may want to use retry the Color Module to adjust the colour of the recovered detail.
  • Then move on to Wavelet Denoise.
Description of Controls:

Define a preset areas of the spectrum you want to use to enhance the detail.
Many of the presets assume SHO (e.g. Hubble Palette) RGB mapping.
  • Default(All) - Uses all of the color data to enhance the detail
  • SHO SII - When using SHO narrowband data - Enhances the detail identified using the SII (red) data.
  • SHO Ha - When using SHO narrowband data - Enhances the detail identified using the Ha (green) data.
  • SHO OIII - When using SHO narrowband data - Enhances the OIII detail identified using the OIII (blue) data.
  • Visual Ha - When using broadband data - Enhances the detail identified using the Ha (red) data.
Specifies the Entropy mapping resolution of the analysis. Higher resolution takes longer to process.
  • Low - If you are trying to highight larger, more general, variations in the image.
  • Medium - If you are trying to highlight medium sized detail.
  • High - If you are trying to highlight small details in the image.
  • Default is Medium.
Channel Selection
Selects the channels which are used in enhancing the detail. Hubble pallette (HSO) is assumed for narrow band, or full visual spectrum.
  • All - Enhances the detail using all the colour data.
  • Red (SHO SII, Vis.HA) - Enhances the detail identified using red data (e.g. SHO SII or Visible Ha)
  • Red+Blue (SHO SII+OIII,Vis.HII) - Enhances the detail identified using the red and blue data (e.g. SHO SII & OIII or Visible HII)
  • Red+Green (SHO SII+Ha) - Enhances the detail identified using the red and green data (e.g. SII & Ha data)
  • Green (SHO Ha) - Enhances the detail identified using the green data (e.g. SHO Ha data)
  • Green+Blue (Vis.O-III, SHO Ha+OIII) - Enhances the detail identified using the green and blue data (e.g. SHO Ha and OIII or visible OIII)
  • Blue (Vis.Reflection, SHO OIII) - Enhances the detail identified using the blue data (e.g. SHO OIII or visible reflection nebulae)
  • Default is 'All' - Uses all channels to identify the detail to enhance.
The overall strength of the increase or decrease of luminance.
  • Increasing the Strength parameter increases the effect.
  • Be careful not to introduce artefacts with the higher values under certain circumstances.
  • Default is 100%. Range is 0% to 1,000%.
Dark/Light Enhance
Selects the balance between brightening the selected channels and darkening areas in order to enhance the detail locally.
  • Minimum 0%/100% - Just brightens to highlight the detail. Use this to just enhance faint nebulosity without darkening the surrounding area.
  • Maximum 100%/0% - Just darkens to highlight the detail.
  • Default is 50%/50% - Both darkens and brightens evenly to highlight the detail.
Midtone Pull Strength
Sets the amount of priority given to the midtones. How much luminance should be pulled towards the midtones.
  • 0% Turns off the midtone filter.
  • Default is 50%. Range is 0% to 100%.
Midtone Pull Filter
Defines the kernel size of the filter that blends the enhanced and non-ehanced detail to give a smooth transition.
  • Default is 20.0 Pixels. Range is 1.0 pixel to 51.0 pixels
Post Reply