Module on Astro Live Stacker

Concepts

Thu, 11 Jun 2026 00:33:39 +0000

Introduction

By the end of this chapter, the basic concepts of ALS will be familiar to you.

You will understand what ALS does and how it does it.

Stacking

Stacking is the process of combining multiple subs of the same target to generate a more detailed and contrasted image than a single sub.

The quality of the result increases as more subs are used.

Comparison of 8 stacking results
The number of stacked subs is indicated at the top left of each image

main controls

Thu, 11 Jun 2026 00:33:39 +0000

Introduction

During this chapter, you will:

get familiar with ALS main controls
Deepen your knowledge on key features

Overview

The ALS control station is the Main Controls interface panel

Located on the left side of the ALS interface, it organizes the most used controls and displays into sections:

Session

Session controls and status
Stack

Stack controls and stack information
Image Server

Image server controls and status
Image Saver

Image saving tools

Reference documentation

Thu, 11 Jun 2026 00:33:38 +0000

Overview

This section contains detailed documentation about ALS bits and bolts

🧠 It elaborates on the concepts introduced at the beginning of the user guide

Modules and Processes

Thu, 11 Jun 2026 00:33:38 +0000

Overview

In here, you will find detailed documentation about ALS modules and processes.

From what a module is to how a process works, you will find everything you need to know about the bits and bolts of ALS.

Modules

An ALS module is an elaborated processing unit responsible for a specific task.

It has its own engine
It can be started and stopped at will
It has access to the settings defined in ALS preferences
Its behavior can be controlled through the ALS interface

Modules are dumb and isolated. They have no knowledge of other parts of the application. They just do their job and report to the application

Scanner

Thu, 11 Jun 2026 00:33:39 +0000

Overview

The Scanner module is the entry point for your subs in ALS.

It is responsible for:

Monitoring the appearance of subs in the scan folder
Loading the detected subs

ℹ️ Existing files are ignored

Files present in the scan folder before the Scanner module is started are not detected

ℹ️ Detection of subs is recursive

Subs are detected regardless of the level of subfolders where they appear within the scan folder

Preprocess

Thu, 11 Jun 2026 00:33:38 +0000

Overview

The Preprocess pipeline handles calibration processes

Configuration

The Preprocess pipeline itself requires no configuration.

The configuration of the calibration processes is managed by the processes themselves. See the Behavior section below.

Control

The Preprocess module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger calibration

Input

Data	Type
sub at queue front	Image

Behavior

Performs calibration processes on the sub:

Output

Calibrated sub is broadcast

Stacker

Thu, 11 Jun 2026 00:33:39 +0000

Overview

The Stacker module handles the alignment and stacking of calibrated subs.

Configuration

	Source	Data type	Required	Default value
Alignment ON/OFF	Interface: Stacking controls	ON/OFF	∅	ON
Stacking mode	Interface: Stacking controls	choices: - mean - sum	YES	mean
Detection threshold	Interface: Stacking controls	integer	YES	25

Control

The Stack module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image
session alignment reference	Image

Behavior

flowchart LR
Start([START])
FirstSub{{First sub of the session?}}
SetAlignReference[Set sub as alignment reference]
CheckShape{{Sub same dimensions as previous result?}}
CheckAlign{{Alignment ON?}}
AlignImage[Align sub]
StackImage[Add sub to Stack]
ComputeStacking[Compute stacking]
PublishReference[Return alignment reference]
PublishResult[Return generated image]
End([END])

Start --> FirstSub
FirstSub -- YES --> SetAlignReference
SetAlignReference --> PublishReference
FirstSub -- NO --> CheckShape
CheckShape -- YES --> CheckAlign
CheckAlign -- YES --> AlignImage
AlignImage --> StackImage
CheckAlign -- NO --> StackImage
StackImage --> ComputeStacking
ComputeStacking --> PublishResult
CheckShape -- NO --> End
PublishReference --> End
PublishResult --> End

classDef bounds fill: #333, stroke: #666, stroke-width: 2px, color: #BBB, font-family: 'Poppins', sans-serif
classDef step fill: #444, stroke: #622, stroke-width:2px, color: #c6c6c6, font-family: 'Poppins',sans-serif
classDef test fill: #444, stroke: #226, stroke-width: 2px, color: #c6c6c6, font-family: 'Poppins', sans-serif

class Start,End bounds
class SetAlignReference,AlignImage,StackImage,PublishResult,ComputeStacking,PublishReference step
class CheckShape,CheckAlign,FirstSub test

Alignment

If alignment is ON

Process

Thu, 11 Jun 2026 00:33:39 +0000

Overview

The Process pipeline handles visual processing tasks applied to the stacking results.

Configuration

The Process pipeline itself requires no configuration.

The configuration of the visual processing tasks is managed by the processes themselves. See the Behavior section below.

Control

The Process module is launched in the background at ALS startup.

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image

Behavior

Performs visual processing tasks on the stacking result:

Save

Wed, 10 Jun 2026 23:25:49 +0000

Overview

The Save module handles the saving on disk of all images generated by ALS.

Its configuration is managed via ALS preferences

Configuration

	Source	Data type	Required	Default value
work folder	Prefs: Output Tab	path to a folder	Yes	∅
web folder	Prefs: Output Tab	path to a folder	Yes	= work folder
file format	Prefs: Output Tab	choices: - TIFF - PNG - JPEG	Yes	JPEG

Control

The Save module is launched in the background at ALS startup

Server

Thu, 11 Jun 2026 00:20:09 +0000

Overview

The Server utility module exposes ALS processing results through a lightweight HTTP and WebSocket service.

It is responsible for:

Publishing the latest processed stacking result and session metrics in the configured web folder
Serving the viewer web application (index.html, JavaScript and icons)
Streaming live new-image notifications to connected browsers over WebSockets
Providing a QR-code friendly URL so that tablets or phones can join the session quickly

The module runs in its own asyncio event loop and accepts concurrent browser clients. It never alters the processing pipeline; it only serves the web image written by the Save module.

Concepts

Thu, 11 Jun 2026 00:33:38 +0000

Introduction

By the end of this chapter, the basic concepts of ALS will be familiar to you.

You will understand what ALS does and how it does it.

Stacking

Stacking is the process of combining multiple subs of the same target to generate a more detailed and contrasted image than a single sub.

The quality of the result increases as more subs are used.

Comparison of 8 stacking results
The number of stacked subs is indicated at the top left of each image

main controls

Thu, 11 Jun 2026 00:33:38 +0000

Introduction

During this chapter, you will:

get familiar with ALS main controls
Deepen your knowledge on key features

Overview

The ALS control station is the Main Controls interface panel

Located on the left side of the ALS interface, it organizes the most used controls and displays into sections:

Session

Session controls and status
Stack

Stack controls and stack information
Image Server

Image server controls and status
Image Saver

Image saving tools

Reference documentation

Thu, 11 Jun 2026 00:33:38 +0000

Overview

This section contains detailed documentation about ALS bits and bolts

🧠 It elaborates on the concepts introduced at the beginning of the user guide

Modules and Processes

Thu, 11 Jun 2026 00:33:38 +0000

Overview

In here, you will find detailed documentation about ALS modules and processes.

From what a module is to how a process works, you will find everything you need to know about the bits and bolts of ALS.

Modules

An ALS module is an elaborated processing unit responsible for a specific task.

It has its own engine
It can be started and stopped at will
It has access to the settings defined in ALS preferences
Its behavior can be controlled through the ALS interface

Modules are dumb and isolated. They have no knowledge of other parts of the application. They just do their job and report to the application

Scanner

Thu, 11 Jun 2026 00:33:38 +0000

Overview

The Scanner module is the entry point for your subs in ALS.

It is responsible for:

Monitoring the appearance of subs in the scan folder
Loading the detected subs

ℹ️ Existing files are ignored

Files present in the scan folder before the Scanner module is started are not detected

ℹ️ Detection of subs is recursive

Subs are detected regardless of the level of subfolders where they appear within the scan folder

Preprocess

Thu, 11 Jun 2026 00:33:38 +0000

Overview

The Preprocess pipeline handles calibration processes

Configuration

The Preprocess pipeline itself requires no configuration.

The configuration of the calibration processes is managed by the processes themselves. See the Behavior section below.

Control

The Preprocess module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger calibration

Input

Data	Type
sub at queue front	Image

Behavior

Performs calibration processes on the sub:

Output

Calibrated sub is broadcast

Stacker

Thu, 11 Jun 2026 00:33:38 +0000

Overview

The Stacker module handles the alignment and stacking of calibrated subs.

Configuration

	Source	Data type	Required	Default value
Alignment ON/OFF	Interface: Stacking controls	ON/OFF	∅	ON
Stacking mode	Interface: Stacking controls	choices: - mean - sum	YES	mean
Detection threshold	Interface: Stacking controls	integer	YES	25

Control

The Stack module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image
session alignment reference	Image

Behavior

flowchart LR
Start([START])
FirstSub{{First sub of the session?}}
SetAlignReference[Set sub as alignment reference]
CheckShape{{Sub same dimensions as previous result?}}
CheckAlign{{Alignment ON?}}
AlignImage[Align sub]
StackImage[Add sub to Stack]
ComputeStacking[Compute stacking]
PublishReference[Return alignment reference]
PublishResult[Return generated image]
End([END])

Start --> FirstSub
FirstSub -- YES --> SetAlignReference
SetAlignReference --> PublishReference
FirstSub -- NO --> CheckShape
CheckShape -- YES --> CheckAlign
CheckAlign -- YES --> AlignImage
AlignImage --> StackImage
CheckAlign -- NO --> StackImage
StackImage --> ComputeStacking
ComputeStacking --> PublishResult
CheckShape -- NO --> End
PublishReference --> End
PublishResult --> End

classDef bounds fill: #333, stroke: #666, stroke-width: 2px, color: #BBB, font-family: 'Poppins', sans-serif
classDef step fill: #444, stroke: #622, stroke-width:2px, color: #c6c6c6, font-family: 'Poppins',sans-serif
classDef test fill: #444, stroke: #226, stroke-width: 2px, color: #c6c6c6, font-family: 'Poppins', sans-serif

class Start,End bounds
class SetAlignReference,AlignImage,StackImage,PublishResult,ComputeStacking,PublishReference step
class CheckShape,CheckAlign,FirstSub test

Alignment

If alignment is ON

Process

Thu, 11 Jun 2026 00:33:38 +0000

Overview

The Process pipeline handles visual processing tasks applied to the stacking results.

Configuration

The Process pipeline itself requires no configuration.

The configuration of the visual processing tasks is managed by the processes themselves. See the Behavior section below.

Control

The Process module is launched in the background at ALS startup.

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image

Behavior

Performs visual processing tasks on the stacking result:

Save

Wed, 10 Jun 2026 23:25:49 +0000

Overview

The Save module handles the saving on disk of all images generated by ALS.

Its configuration is managed via ALS preferences

Configuration

	Source	Data type	Required	Default value
work folder	Prefs: Output Tab	path to a folder	Yes	∅
web folder	Prefs: Output Tab	path to a folder	Yes	= work folder
file format	Prefs: Output Tab	choices: - TIFF - PNG - JPEG	Yes	JPEG

Control

The Save module is launched in the background at ALS startup

Server

Thu, 11 Jun 2026 00:20:09 +0000

Overview

The Server utility module exposes ALS processing results through a lightweight HTTP and WebSocket service.

It is responsible for:

Publishing the latest processed stacking result and session metrics in the configured web folder
Serving the viewer web application (index.html, JavaScript and icons)
Streaming live new-image notifications to connected browsers over WebSockets

The module runs in its own asyncio event loop and accepts concurrent browser clients. It never alters the processing pipeline; it only serves the web image written by the Save module.

Concepts

Thu, 11 Jun 2026 00:33:39 +0000

Introduction

By the end of this chapter, the basic concepts of ALS will be familiar to you.

You will understand what ALS does and how it does it.

Stacking

Stacking is the process of combining multiple subs of the same target to generate a more detailed and contrasted image than a single sub.

The quality of the result increases as more subs are used.

Comparison of 8 stacking results
The number of stacked subs is indicated at the top left of each image

main controls

Thu, 11 Jun 2026 00:33:39 +0000

Introduction

During this chapter, you will:

get familiar with ALS main controls
Deepen your knowledge on key features

Overview

The ALS control station is the Main Controls interface panel

Located on the left side of the ALS interface, it organizes the most used controls and displays into sections:

Session

Session controls and status
Stack

Stack controls and stack information
Image Server

Image server controls and status
Image Saver

Image saving tools

Reference documentation

Thu, 11 Jun 2026 00:33:39 +0000

Overview

This section contains detailed documentation about ALS bits and bolts

🧠 It elaborates on the concepts introduced at the beginning of the user guide

Modules and Processes

Thu, 11 Jun 2026 00:33:39 +0000

Overview

In here, you will find detailed documentation about ALS modules and processes.

From what a module is to how a process works, you will find everything you need to know about the bits and bolts of ALS.

Modules

An ALS module is an elaborated processing unit responsible for a specific task.

It has its own engine
It can be started and stopped at will
It has access to the settings defined in ALS preferences
Its behavior can be controlled through the ALS interface

Modules are dumb and isolated. They have no knowledge of other parts of the application. They just do their job and report to the application

Scanner

Thu, 11 Jun 2026 18:38:13 +0000

Overview

The Scanner module is the entry point for your subs in ALS.

It is responsible for:

Monitoring the appearance of subs in the scan folder
Loading the detected subs

ℹ️ Existing files are ignored

Files present in the scan folder before the Scanner module is started are not detected

ℹ️ Detection of subs is recursive

Subs are detected regardless of the level of subfolders where they appear within the scan folder

Preprocess

Thu, 11 Jun 2026 00:33:39 +0000

Overview

The Preprocess pipeline handles calibration processes

Configuration

The Preprocess pipeline itself requires no configuration.

The configuration of the calibration processes is managed by the processes themselves. See the Behavior section below.

Control

The Preprocess module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger calibration

Input

Data	Type
sub at queue front	Image

Behavior

Performs calibration processes on the sub:

Output

Calibrated sub is broadcast

Stacker

Thu, 11 Jun 2026 17:57:08 +0000

Overview

The Stacker module handles the alignment and stacking of calibrated subs.

Configuration

	Source	Data type	Required	Default value
Alignment ON/OFF	Interface: Stacking controls	ON/OFF	∅	ON
Stacking mode	Interface: Stacking controls	choices: - mean - sum	YES	mean
Minimum matches	Interface: Stacking controls	integer	YES	25

Control

The Stack module is launched in the background at ALS startup

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image
session alignment reference	Image

Behavior

flowchart LR
Start([START])
FirstSub{{First sub of the session?}}
SetAlignReference[Set sub as alignment reference]
CheckShape{{Sub same dimensions as previous result?}}
CheckAlign{{Alignment ON?}}
AlignImage[Align sub]
StackImage[Add sub to Stack]
ComputeStacking[Compute stacking]
PublishReference[Return alignment reference]
PublishResult[Return generated image]
End([END])

Start --> FirstSub
FirstSub -- YES --> SetAlignReference
SetAlignReference --> PublishReference
FirstSub -- NO --> CheckShape
CheckShape -- YES --> CheckAlign
CheckAlign -- YES --> AlignImage
AlignImage --> StackImage
CheckAlign -- NO --> StackImage
StackImage --> ComputeStacking
ComputeStacking --> PublishResult
CheckShape -- NO --> End
PublishReference --> End
PublishResult --> End

classDef bounds fill: #333, stroke: #666, stroke-width: 2px, color: #BBB, font-family: 'Poppins', sans-serif
classDef step fill: #444, stroke: #622, stroke-width:2px, color: #c6c6c6, font-family: 'Poppins',sans-serif
classDef test fill: #444, stroke: #226, stroke-width: 2px, color: #c6c6c6, font-family: 'Poppins', sans-serif

class Start,End bounds
class SetAlignReference,AlignImage,StackImage,PublishResult,ComputeStacking,PublishReference step
class CheckShape,CheckAlign,FirstSub test

Alignment

If alignment is ON

Process

Thu, 11 Jun 2026 00:33:39 +0000

Overview

The Process pipeline handles visual processing tasks applied to the stacking results.

Configuration

The Process pipeline itself requires no configuration.

The configuration of the visual processing tasks is managed by the processes themselves. See the Behavior section below.

Control

The Process module is launched in the background at ALS startup.

Source	Type	Response
sub(s) in queue	Event	trigger processing

Input

Data	Type
sub at queue front	Image

Behavior

Performs visual processing tasks on the stacking result:

Save

Wed, 10 Jun 2026 23:25:50 +0000

Overview

The Save module handles the saving on disk of all images generated by ALS.

Its configuration is managed via ALS preferences

Configuration

	Source	Data type	Required	Default value
work folder	Prefs: Output Tab	path to a folder	Yes	∅
web folder	Prefs: Output Tab	path to a folder	Yes	= work folder
file format	Prefs: Output Tab	choices: - TIFF - PNG - JPEG	Yes	JPEG

Control

The Save module is launched in the background at ALS startup

Server

Thu, 11 Jun 2026 00:20:09 +0000

Overview

The Server utility module exposes ALS processing results through a lightweight HTTP and WebSocket service.

It is responsible for:

Publishing the latest processed stacking result and session metrics in the configured web folder
Serving the viewer web application (index.html, JavaScript and icons)
Streaming live new-image notifications to connected browsers over WebSockets
Providing a QR-code friendly URL so that tablets or phones can join the session quickly

The module runs in its own asyncio event loop and accepts concurrent browser clients. It never alters the processing pipeline; it only serves the web image written by the Save module.