StarXTerminator Version 2/AI 11 Release Notes

StarXTerminator 2.0 with AI version 11 is now released for both PixInsight and Photoshop/Affinity Photo, and is available for download. This is a major update with the following changes:

  • All-new neural network architecture, trained from scratch on a much larger data set, including data from the James Webb and Hubble space telescopes.
  • Improved handling of extremely large, bright stars and long diffraction spikes.
  • Improved preservation and recovery of image detail from the glare of bright stars.
  • Improved detection and removal of stars with guiding errors and mis-registration of RGB channels, such as when processing exposures tracked on moving comets.
  • Improved differentiation of stellar vs. non-stellar structures. More “faint fuzzies” and detailed nebula structure is retained.
  • Added a “Large Tile Overlap” option to increase the overlap between processing tiles to 50% from the default 20%. On most images, the default is sufficient to prevent artifacts at tile edges. On some images, particularly those with extremely large, bright stars, dense/busy star fields, and large, very bright objects with high contrast to their surroundings (e.g., M42), the larger tile overlap will produce a much smoother result. Note that this will increase processing time significantly, on the order of 3x. Only select this option if you notice tiling artifacts with the default setting.

PixInsight-specific changes:

  • Completely revamped noise matching algorithm. Bright stars have little to no noise information in their saturated cores, and too much (Poisson) noise in their halos. This algorithm fills in noise where the stars once were that closely matches that of the rest of the image in spatial frequency and color content. You may find it difficult to tell where the stars used to be. This module is only available in the PixInsight version.
  • Processing of linear and nonlinear images is now automatic, and the “Linear” checkbox has been removed. You will need to update the source code of any scripts or process icons you have created to remove the P.linear parameter.
  • Improved handling of images with varying dynamic range and star profiles, particularly those integrated using drizzle. Note: images stretched using a generalized hyperbolic stretch (GHS), and sometimes arcsinh, can produce star profiles that are nearly indistinguishable from many small elliptical galaxies and may not be removed by StarXTerminator. If you plan to perform GHS or arcsinh stretching in your workflow, perform star removal prior to stretching for best results.
  • The STF of the target image is translated to star images, if generated. Side note: don’t auto-stretch star images. It destroys this STF information and gives a false impression of residual artifacts at very low levels.
  • The astrometric solution and color profile of the target image, if any, is replicated in star images.
  • The AI11 neural network comes in three variants to maximize compatibility with various computer hardware. Use whichever will work on your machine and suits your purposes:
    • The full version produces the best results, but makes intensive use of compute and memory resources, and may take a very long time or not work at all on older or less-endowed machines.
    • The “lite” version uses about 4x less memory and may improve execution time on less-endowed machines.
    • The “lite.nonoise” version omits the noise matching module, and will significantly improve execution time, but areas where stars once were will have little to no noise. This is generally not an issue if noise reduction has been or will be performed on the image.

Photoshop-specific changes:

  • The StarXTerminator download now comes as an installation package rather than a collection of files that you have to manually install. This will automatically clean up any older versions and install StarXTerminator for all versions of Photoshop and/or Affinity photo present on your machine.
  • The “Download AI” button has been removed: the AI neural network is included in the installation package.

Updating PixInsight

PixInsight updates should be automatic if you have the StarXTerminator repository entered into PixInsight. If you haven’t received the update, follow these instructions.

Updating Photshop/Affinity Photo

Photoshop/Affinity Photo updates can be downloaded here:

Special note for Windows Photoshop/Affinity users

Some very old machines with CPUs made before ~2013, and even some modern lightweight machines with scaled-back CPUs, will not run StarXTerminator 2.0. If you have NoiseXTerminator and it works on your machine, then StarXTerminator 2.0 will work, too. You can download a free trial of NoiseXTerminator as a compatibility test here:

If in doubt, contact support with the model of CPU that your machine has before updating. The version you currently have will of course continue to work, but if you install the new version, it will be deleted.

Special note for MacOS users

The AI11 neural network uses advanced techniques that require MacOS 11 (Big Sur) or later.

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