PixInsight 1.8.9-2 / Build 1583 Released

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Juan Conejero

PixInsight Staff
Staff member
Hi all,

*** Note: Please see also the announcement for 1.8.9-2 build 1584, which we have released today to fix a minor bug.

Today we released a new PixInsight version: 1.8.9-2 build 1583 (2023 September 18). This maintenance/bugfix release solves several problems detected in previous builds of the current 1.8.9-2 version. It also adds a few new features.

Please refer to the previous announcements for complete information on new features, recommended platforms, and known problems for PixInsight 1.8.9-2:

Official announcement of PixInsight version 1.8.9-2
Official announcement of PixInsight version 1.8.9-2 build 1579


Installation packages for PixInsight 1.8.9-2 build 1583 are now available to all licensed users for Linux, macOS and Windows:


As happens with all updates to the PixInsight core application, this version cannot be downloaded as an application update. You must install version 1.8.9-2 manually:
  • Linux: The installation packages are xz-compressed tar archives (.tar.xz). To install one of these archives, just extract its full contents on any directory, preferably on one located under your home directory. Then become root and run the installer program from a terminal. Normally you should just type 'yes' and press Enter to accept the default settings. Say ./installer --help for detailed information on command-line arguments.

  • macOS: If you have a previous version of PixInsight already installed, you must uninstall it by moving the /Applications/PixInsight folder to trash (also known as bin on macOS 10.15 and later). Run the .pkg installation package and follow the instructions. All our macOS installation packages are digitally signed with our corporate Apple developer certificate and have been notarized by Apple.

  • Windows: Run the installation package for version 1.8.9-2 and follow the instructions. The installer will remove a previous version automatically, so there is no need to uninstall it first. All executable files in the PixInsight distribution for Windows, as well as our Windows installation packages, have been signed with our corporate Extended Validation (EV) code signing certificate.
If you have a 1.8.6 version or newer already installed, this new version does not require a license reactivation. If you are still using a 1.8.5 version or older, see the official 1.8.6 version announcement for a detailed description of our new licensing system. See also FAQ 2.10 for additional information on license reactivations.

Bug Fixes
  • Fixed wrong calculation of the amount of physical RAM available on macOS in some cases.

  • Fixed wrong calculation of the amount of disk space available on macOS for external and network volumes.

  • The Select All (Cmd+A) command is now available on native macOS file open dialogs.

  • On Windows, the number of available logical processors was only calculated for the first NUMA node in multiprocessor systems. We now provide access to all available logical processors in the system.

  • The XISF support module (and corresponding PCL implementation) was writing nonstandard attributes for the RGBWorkingSpace XML element. We now adhere to the XISF standard strictly. RGBWorkingSpace elements in XISF images generated with previous versions of PixInsight are fully supported.

  • Fixed invalid declination coordinate for Messier 2 / NGC 7086 in annotation databases.

New Features

New Settings System

We have designed and implemented a new settings system that no longer depends on Qt (QSettings class). Settings data are now stored and maintained using a high-performance dictionary tree structure serialized as special XML files with the same format on all platforms. This new system is significantly more efficient, both in terms of speed and storage space, and more controllable.

The first time you run this new version, it will scan system directories looking for an old settings file (.ini or .conf files in INI format on Windows and Linux, .plist files on macOS). If one of these files is found and a new XML settings file is not, old settings will be imported automatically. The import process uses heuristics to deduce the data type of each key/value settings pair and can correctly import all Qt settings files that we have tested. This means the transition should be transparent for all users on all platforms, and no existing configurations will be lost.

The new settings XML files are generated on the same folders used by previous versions:




Each settings file stores data exclusively for a running instance of the PixInsight core application (also known as instance slot). There can be 256 instances of PixInsight running simultaneously on a user account, so in theory, a user could have 256 settings files.

The filename of a settings file must satisfy the following pattern:


where <nnn> is an instance slot in the [1,256] range, represented as three digits left-padded with zeros (that is, from 001 to 256).

Note that this system has several important advantages not available with the old Qt-based settings. One of them is that one can easily propagate settings among application instances. For example, if you copy "core-001-pxi.settings" to "core-002-pxi.settings", the second application instance will receive an exact copy of the current configuration for the first instance.

Another advantage is that maintaining settings files is much easier now because we can generate them in a readable format that can be edited and modified easily with a good code editor.

A new Settings and Cache Data section in the Preferences process allows us to control the generation of settings files:


In this section we can define the period between automatic synchronizations of modified settings data with disk files, which is 30 seconds by default. Note that settings files are not synchronized as often as with the old Qt-based system. An automatic synchronization only happens when the internal dictionary tree is modified, which does not necessarily occur when a key/value settings pair is created or redefined. Of course, the settings file is automatically updated if necessary upon application exit.

You can also turn off minification to generate easily editable XML code and compression of large binary and text data blocks. The tooltips for these options provide more helpful information.

We also have a new main menu command, Edit > Write Settings File, that allows us to force an update of the core settings file anytime.


VSync Control

This version of the PixInsight core application allows controlling the synchronization of screen drawing operations with the vertical refresh rate of screen video frames. This is often referred to as VSync for short. By default, the application attempts to force VSync to one video frame upon start. This behavior can be controlled with a new --swap-interval command-line parameter:


      Specifies the minimum number <n> of video frames displayed before video
      buffer swaps. This can be used to synchronize OpenGL drawing to the
      vertical refresh rate of the screen.

      Specifying 'disable' or zero turns off vertical refresh synchronization.
      Specifying 'auto' or a negative value applies default system settings. A
      value > 0 specifies the number of video frames for synchronization. The
      default value is 1 on Linux and Windows; 'auto' on macOS. The supported
      range is [-1,8].

      Note: This functionality may not be supported by the underlying platform
      or be disabled by platform configuration settings. In such a case, this
      option will be silently ignored.

We hope most of the reported slow display rendering problems will be solved with this feature. If necessary, specifying --swap-interval=disable can be used to turn off VSync in special situations, although the default VSync of one frame should normally be optimal on Linux and Windows. We don't force VSync on macOS by default because the factory default settings are generally optimal on all Mac machines.

See also the instructions we have provided to control VSync by changing the graphics driver configuration on Windows.

Improved Image Rendering

This version includes an optimization of the number of threads used for core image rendering tasks. Rendering refers to the generation of the bitmaps painted on the screen for each image window, not the painting operations. This is a critical task with a strong repercussion on the user's experience.

We have discovered that in previous versions, there were cases in which an excessive number of threads was used, leading to suboptimal performance by rendering too few pixels per thread. In this version, we have evaluated the cost of the different rendering tasks versus the cost of generating and maintaining running rendering threads. No thread renders now less than 16K - 64K pixels, depending on the visualization mode and conditions. This should provide a smoother image navigation experience on all platforms.

Improved Generation of FITS Header Keywords in XISF Files

The following FITS keywords are no longer stored in XISF files:


These structural and mandatory keywords make no sense outside a FITS file. By not storing them, we prevent the possibility of confusion caused by contradictory values.

Configurable Order of Yes/No and OK/Cancel Buttons in Message Boxes

By popular demand, we have implemented new preferences settings to define the order of these buttons in message box dialogs.




Thank you for your attention,

The PixInsight Team at Pleiades Astrophoto S.L.
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