AstroDMx Capture - Astro Imaging under Linux


The AstroDMx Capture project was originally started to produce a stable astro imaging application for use with the Imaging Source DMK, DFK and DBK range of cameras. Since then, the project has grown into a fully featured astronomical image capture application for the Linux operating system. AstroDMx Capture for Linux is a long term project and will be adding additional features and improving the camera support on a regular basis.

AstroDMx Capture has been written from the ground up in C++ / wxWidgets with performance and reliability as some of the most important factors. For example, the software automatically detects if a camera has gone offline. If an offline camera is detected then the software will automatically reinitialise the camera with all the previous settings and continue as if nothing has gone wrong. This function works even if your camera was accidentally disconnected and reconnected during a capture session.

The software currently supports saving data in both 8 and 16-bit formats, off-chip frame integration, dedicated function for capturing both dark and flat frames, real-time frame calibration, over-exposure indication, a custom colour guide reticle, Region of interest nudge during capture, off camera debayering using a high-quality linear interpolation algorithm, automatic debayer pattern selection and many more features. For a full list of supported features please see the table below.

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Key Features of AstroDMx Capture for Linux

The following is a short list of some of the key features of AstroDMx Capture for Linux. Not all functions are detailed here but all features will be in the software documentation once it has been completed.

  • User Interface

AstroDMx Capture has been design to be user friendly.

Most of the controls are dynamic, and so only the controls relevant to the connected camera are visible. For convenience, the camera controls are organised into logical groups, all of which can be minimised to save space. If the computer monitor is not large enough and too many controls are maximised, then a scrollbar will appear which allows the user to see all available controls quickly and efficiently.

  • Startup Delay

Some Video4Linux cameras can take a long time to initialise. AstroDMx Capture, therefore, has a startup delay function. If a camera fails to connect properly or the software displays error messages then the startup delay function can be changed.

  • Heartbeat Monitor

The ZWO USB2 cameras works perfectly in AstroDMx Capture. However, the camera can be temperamental, especially if the computer's USB ports are loose. A heartbeat monitor has been programming into AstroDMx Capture. This feature is enabled by default and regularly checks to see if the connected camera is still streaming. If the software detects that the camera has gone offline, then the camera is automatically reset and reinitialised with its existing settings. If the software is currently capturing, then the capture is paused while the camera reinitialises and then continues where it left off.

This function works for any camera and even works if a camera is accidentally disconnected during use. The camera heartbeat function can be disabled during the connection routine if required.

  • Camera Controls

All camera controls within AstroDMx Capture are context aware. That is to say, only controls valid to the connected camera and its specific setup are shown. For example, if a 12-bit camera is connected in 8-bit mode, then 16-bit options will not show in the UI.

The user can specify the exposure control's range depending on the circumstances and the particular requirements of the intended imaging session. The full range is listed below but is dependent upon the camera's specification, and so not all will be necessarily visible.

  • Microseconds
  • 1 ms to 15 ms
  • 15 ms to 100 ms
  • 100 ms to 250 ms
  • 250 ms to 500 ms
  • 1 ms to 1000 ms
  • 1s to 5s
  • 5s to 15s
  • 15s to 30s
  • 30s to 60s
  • 60s to 120s
  • 120s to 240s
  • 240s +

The software supports all the usual camera controls such as gain, gamma, brightness and contrast etc. If supported by the camera the software also shows controls for the following: USB Bandwidth optimisation, Region of Interest, Chip Temperature, Binning, Realtime Debayering, 16-bit display and save optimisation, together with various other controls.

Each camera control can be reset to the camera's default by right-clicking the control's slider.

The software supports image flipping and flipping, scaling of the real-time display and shows a real-time frame rate. If a camera has a larger resolution than the real-time display, then the display output is scaled on startup.

If an object is drifting, the Region of Interest can be nudged during capture. To use this feature, click inside the log window within the capture controls dialog and then use the cursor controls to nudge the ROI. Once the ROI range has been exceeded a message appears on the live preview screen.

  • Histogram

The software supports a fully functional histogram. The histogram has the following functionality:

  • Modes: Linear and Logarithmic
  • Channels: Red, Green, Blue, RGB Average, Luminance, RGB combined and greyscale
  • Plots Modes: Dotted line, filled colour, RGB overlay, RGB merge
  • Histogram image is saved as a TIFF when capture completes
  • Histogram scales when the application is maximised or the control area is made larger or smaller.
  • Histogram can be disabled
  • Markers and Guides

It is possible for AstroDMx Capture to indicate to the user if part of an object has reached saturation. Saturated areas are show as one of three different predefined colours or can be set to any colour deemed appropriate by the user. Saturation indication is only visible on the real-time display and will not be present in the saved output. Some cameras don't saturate at the usual expected value, in order to fix this, the software has a saturation sensitivity function. These options are available from the drop-down menus.

AstroDMx Capture also has a reticle which is designed to say dead centre regardless of the size of the UI or the scale factor of the real-time display. The reticle can be shown in one of three predefined colours or can be set to use any colour deemed appropriate by the user. This option is available from the drop-down menus.

  • Filter Wheels

Currently, the software supports the ZWO range of filter wheels. In future releases, the software will support any ASCOM (INDI) compliant filter wheel.

The software allows the user to give an arbitrary name to each filter and provides a quick and convenient method to change filters during capture. If the user enters the exposure ratios of their filters, the software will automatically adjust the exposure based on the value entered. The name given to the filter will be appended to the file name when saved.

  • Output Settings

AstroDMx Capture can save in the following formats: SER 8 and 16-bit, AVI, Windows Bitmap, TIFF 8 and 16-bit and FITS.

The software allows the user to specify custom metadata for FITS output as well as automatically adding camera specific metadata (Exposure, Gain, Gamma etc) to the FITS header.

The AVI processor in AstroDMx Capture has been written from the ground up and does not require any external dependencies. Furthermore, it only outputs uncompressed AVI files because compression is not usually wanted or required in any Astronomical data.

Registax 5 and 6 running under current versions of Wine cannot open AVIX (Extended AVI). The older standard is usually limited to 1GB. To avoid this limitation, AstroDMx Capture can output two AVI formats. The first is a standard AVIX file which applications such as Autostakkert! can open. The second is a custom AVI which makes it fully compatible with Registax under Wine. AVI files in this mode are limited to 2GB instead of the usual 1GB. When using the custom AVI mode, the image will be inverted, however, the image can be flipped.

The software will output a log file which contains information about the specific capture session.

  • Run Modes

AstroDMx Capture provides three run modes. They are as follows:

  • Frame Limit - To capture a specific number of frames
  • Time Limit - To capture as many frames as possible until the user specified time has elapsed
  • Timelapse - To capture a specific number of frames after a specified time interval
  • Manual - To capture an infinite number of frames
  • File Naming

AstroDMx Capture has a dynamic file naming system. It allows for a user specified file prefix, configurable file index, timestamped files in two different formats and saves individual files (Not AVI or SER) into a timestamped subdirectory. This subdirectory is created each time a new dataset is captured.

The timestamp and subdirectory are optional.

  • Debayering Options

AstroDMx Capture can debayer the camera's output and display it on the screen using one of three algorithms. It is also capable of saving the fully debayerd output as a standard RGB file using either a high-quality linear interpolation or a bilinear interpolation algorithm.

For performance reasons, the software either allows the user to disable real-time debayering but have the display debayerd using a lower quality, less resource hungry debayering algorithm (Nearest Neighbour) while having the output saved as raw, or choose not to have the display debayered. If no debayering is selected then the display will show a monochrome undebayered image.

The software works with four debayer patterns. RGGB, GBRG, GRGB and BGGR. The software can automatically discover the correct bayer pattern or the user can specify it manually.

Supported Hardware

USB Astronomy Cameras

  • QHY 5-II-M
  • QHY 5L-II-M
  • QHY 5-II-C
  • QHY 5L-II-C
  • Other QHY cameras should work (Cooling functionality not yet implemented)
  • DMK 21AU04.AS (8 bit ADC)
  • DFK 21AU04.AS (8 bit ADC)
  • DBK 21AU04.AS (8 bit ADC)
  • Other DMK, DFK and DBK cameras should work
  • ZWO ASI120MC (USB2.0, 12 bit ADC)
  • ZWO ASI120MC-S (USB3.0, 12 bit ADC)
  • ZWO ASI120MM-S (USB3.0, 12 bit ADC)
  • Other ZWO cameras will probably work (Cooling has not been implemented in this version)
  • Bresser MicrOcular Full HD Digital Camera (8 bit ADC)

Please note, ZWO have implemented its USB2 cameras to use a nonstandard maxpacket size. Therefore, for the USB2 ZWO cameras you must follow the procedure detailed under "Important Note: ZWO USB2 Cameras" on the download page.

USB cameras

  • ELP 1.3Mp CMOS board-level HD USB camera (8 bit ADC)
  • Lucky Zoom 5Mp microscope USB CMOS camera (8 bit ADC)
  • Vimicro USB2.0 UVC PC camera (e.g. Maplin USB2.0 Microscope) (8 bit ADC)

USB Capture cards

  • KWORLD DVD MAKER 2 (8 bit ADC)
  • UVC Capture Cards (8 bit ADC): Hardware dependent but the software can support the following:
    • Motion-JPEG (8 bit ADC)
    • YUYV (8 bit ADC)
    • Bayer Formats: RGGB, GBRG, GRBG and BGGR.

USB webcams

  • Sweex WC066 HD webcam (8 bit ADC)
  • Sweex WC070 ViewPlus (8 bit ADC)
  • Philips SPC900NC including SPC800 and Philips 740 flashed to SPC900NC (8 bit ADC)
  • Philips 740 ToUCam Pro (mono feed only) map YUYV to greyscale for true mono. (8 bit ADC)
  • Philips 690 Vesta Pro Webcam (8 bit ADC)
  • Logitech HD C525 (8 bit ADC)
  • Microsoft LIFECAM 2 (8 bit ADC)
  • Creative Webcam Live (8 bit ADC) Bayer output only.
  • Creative Webcam Live (8 bit ADC) JFIF/JPEG output only
  • All video for Linux cameras should work.

Motorised Filter Wheels

  • ZWO Range of motorised filter wheels

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Planned Hardware Support

  • Atik range of 16-bit deep sky cameras
  • Lumenera range of Astronomical Cameras
  • INDI Support


AstroDMx Capture - Astro Imaging under Linux Screenshot 1

A screenshot of AstroDMx Capture with a green reticle selected

AstroDMx Capture - Astro Imaging under Linux Screenshot 2

A screenshot of AstroDMx Capture with a blue reticle and red saturation indicators.

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Known Issues

  • Version Due to an issue with the ZWO SDK, the heartbeat monitor does not work and will be automatically disabled when a ZWO camera is connected. If the ZWO camera goes offline, for example, due to a bad USB bandwidth setting, the camera will not automatically reset. If this happens then the user will need to reconnect the camera and then restart the software. All other cameras will be automatically reset and continue from the previous settings if they encounter a issue which causes them to go offline, for example, a loose USB cable.
  • All Versions: If multiple camera controls are changed during a long exposure then the last control will take effect, all others will be cancelled. For example, if the user changes the exposure to one minute and then immediately changes the gain, then the exposure control will be cancelled. To avoid this issue, change one control and wait for the exposure to complete. This behaviour will be changed in a future version.

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