Develop Module Use

Notes from users, documentation addendums.
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Develop Module Use

Post by Guy »

Here are some notes relating to using the Develop module.
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 easily access similar notes on the other StarTools modules see StarTools Main Window Use.

Develop Module

  • To apply a global stretch to the image either for inspection or as the final global stretch. Manual controls allow control of the stretching process.
For a general overview see Develop: Stretching with Photographic Film Emulation
Develop allows a more manually controlled global assisted stretching than AutoDev.
Develop automatically detects the white and black point and ensures the signal never clips.

Useful Sources
The Unofficial guide is also a good source of help. It relates to version 1.3.5 so there may have been some changes. The notes below relate to StarTools version 1.4.
The processing tutorial M33 in LRGB describes the use of the Develop module between about 4m18s and 4m48s.

When to use:
  • In place of AutoDev where you have difficulty getting the results you want with AutoDev. Principal causes are:
    - There is no region of interest with sufficient detail for AutoDev to use
    - There is a lot of noise which disrupts AutoDev operation
  • For the initial global stretch - after loading the image
  • For the final global stretch - after using the Wipe module
  • For adding back an artificial skyglow - at the end of processing
Example Workflow:
AutoDev-{Band/Lens}-Bin-Crop-Wipe-AutoDev(or Develop)-{Decon/Sharp/Contrast/HDR/Flux/Life}-Color-{Filter}-Denoise-{Layer/Magic/Heal/Repair/Synth}
Key: {...} optional modules

This is a way of using the module which should give good results in most cases:
  • Increase Digital Development to set the black point of the global stretch - The 'Home In' button usually finds a good value.
  • Increase Dark Anomaly filter so the noise and other dark anomalies are ignored - usually when the background stops darkening.
  • Usually all other parameters work best with their default settings - but try changing them as described below if you want.
  • If you make a mistake, the 'Reset' button discards all the changes since you started using the module.
  • 'Keep' the result when you are happy with it - unless you plan to use the Band module next.
What result to look for:
Initial global stretch - AutoDev will highlight any of the following:
  • Stacking Artefacts - remove later with Crop module
  • Colour bias (remove this later with the Wipe module)
    - red or yellow/brown cast - skyglow that has been white balanced
    - teal, blue or green cast - skyglow that has not been white balanced
    - bright blue-green cast - skyglow filtered using a light pollution filter
    - missing yellow (e.g. no yellow stars) - indicates use of light pollution filter
  • Vignetting, Amp Glow - remove these later with the Wipe module
  • Dust specks - remember to mask these out when using the Wipe module
  • Noise
  • Banding - use the Band module next - but don't 'Keep' the Develop module result.
  • Debayering Problems - checkerboard pattern. See description here
  • Coma - fix later with the Lens module
Final global stretch - look for:
  • Good dynamic range in the area of interest
  • Make sure you bring out the faintest detail you want to see - the brighter details will be brought out by other modules
  • Look for controlled noise in the background - if not, go back and do a less aggressive stretch (by reducing the Digital Development setting)
  • Colour Bias, Vignetting, Dust specks, etc. should be well controlled or removed by this stage.
Ways of getting better results:
  • Use Flats and Darks when creating the original image
After Use:
  • After the initial global stretch - use the Band module if needed - then use the Lens, Bin, Crop and Wipe modules as needed.
  • After the final global stretch - Consider using the Decon, Sharp, Contrast, HDR modules as needed.
Description of Controls:

Digital Development:
Emulates the response of film
  • Defaults to Off. Range is Off(0.00%) to 100.00%.
  • Use the 'Home In' button or change the slider to adjust the black point of the global stretch of the image.
Home In:
  • Intelligently homes in on the optimum setting for Digital Development. Repeat until you get the result you want.
Use this control to do a simple Gamma non-linear stretch. Used as an alternative to Digital Development control.
  • Defaults to 1.00. Range is 0.00 to 10.00.
  • Leave at 1.00 if using Digital Development.
  • If not using Digital Development - set to 2.2 for correct conversion of linear data so that it appears linear on-screen. Set to approx. 0.46 to undo a JPEGs gamma curve.
Dark Anomaly Filter:
Controls the filtering of Dark Anomalies so that they don't interfere with the Develop operation. Described further here.
Dark Anomalies are anything that is darker than the galactic background. Examples are: Dead pixels, stacking artefacts. dust specks, scratches, trees, mountains.
  • The Dark Anomaly Filter can remove small dark anomalies. For larger dark anomalies you will need to use the Heal or Crop modules.
  • Defaults to 'Off'. Range is Off to 20.0.
  • Increase the value until the image stops darkening. Maximum 20.0 pixels. This ensures that the Dark Anomalies are represented below the darkest point of real data.
Dark Anomaly Headroom:
Defines the percentage of the original value a dark anomaly now occupies. This frees up more dynamic range for subject data.
  • Defaults to 5%. Range is 0% to 100%.
  • Keep above 0% - to avoid clipping.
White Calibration:
Specifies how the Develop module decides on the white point of the global stretch of the image.
  • 'Use Stars' - look for big bright stars
  • 'Use Dark Anomaly Filter (May White Clip)' - use if there are no bright stars and the brightest features are hot pixels. Uses the Dark Anomaly Filter to filter out these white anomalies as well.
    - Requires the Dark Anomaly Filter to be active.
  • Defaults to 'Use Stars'
Colour Channel Luminance Contribution:
For colour images Develop uses the RGB channels to create luminance data on which to do the stretch.
  • If one of the channels is unreliable (due to Chromatic Aberration or lack of Infra Red) then its influence should be reduced.
  • These controls have no effect on monochrome images and so in this case are disabled.
  • Defaults to 100%. Range is 0% to 500%.
Luminance Contribution Settings:
  • Red Luminance Contrib. - Sets the relative influence of the Red channel.
  • Green Luminance Contrib. - Sets the relative influence of the Green channel.
  • Blue Luminance Contrib. - Sets the relative influence of the Blue channel.
Re-introduces an artificial sky glow.
  • Best to leave this to just before saving the image.
  • Defaults to 0%. Range is 0% to 50%.
Background Notes:
The Develop module, along with the AutoDev, Contrast and HDR modules, provide automated stretching at all levels of detail. These modules replace the traditional curve-based adjustment of stretching.
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