During the current development of AstroDMx Capture for Linux, macOS and Windows, we have been in feature freeze following the implementation of motion detection, as Nicola has been substantially refactoring the code and bringing it into a single code base. However, recent experience with a nest box camera and a digital microscope has led us to make two exceptions that will facilitate the use of AstroDMx Capture for these two types of use of the software.
AstroDMx Capture for Linux streaming data from a digital microscope
which has no camera controls
AstroDMx Capture has long had set of display controls that enable the user to change the gamma, brightness, and contrast of the display in a non-destructive way. That is, the display controls only effect the display, but not the saved data.
However, there are some cameras such as the nest box endoscope type camera that we have been using, and the digital microscope, that have minimal, or even no controls, and are in fully automatic mode. We have found that the ability to control the gamma and contrast, of the display has enabled much clearer views to be obtained of the nest box, particularly in low light.
We decided to allow the user to enable the saving of the display, software-controlled data, thus effectively adding controls to the camera. This saving function can be toggled and only applies to 8-bit data. This is effectively what capture cards do with the data streaming from an analogue video camera, providing added control over the video stream. Nicola has implemented this code and has, in addition to gamma, brightness and contrast, also implemented a software gain control.
Some camera manufacturers such a ZWO removed the gamma control from their SDK even though internally, the camera is capable of gamma control. The purists say that gamma control is not necessary because that aspect of an image can be dealt with in post processing. It is my opinion that gamma control is very useful at capture time and allows a better balance between gain and exposure control as one is able to see regions of intermediate brightness such as the region close to the terminator in a lunar image, without increasing the exposure and in the process, overexposing the brighter regions. Also, in H-alpha solar imaging, control of gamma can help see the structures that occupy various regions of the dynamic range.
Screenshot of AstroDMx Capture for Linux capturing lunar data with a ZWO ASI178MC camera, with the software controls enabled for viewing and saving, and with the gamma increased above the default for the camera
Closer view
Screenshot of AstroDMx Capture for Linux capturing lunar data with a ZWO ASI178MC camera, with the software controls disabled, and with the gamma at the default for the camera
Closer view
Four overlapping panes were captured as 1000-frame SER files. The best 90% of the frames in the SER files were stacked in Autostakkert!, wavelet processed in Registax 6, stitched into a single, 4-pane mosaic and post processed in the Gimp 2.10.
16.8% waxing, crescent Moon
Another feature has been added that required a slight change to the GUI. This is the addition of a Snapshot button. This will be of limited value for astronomy unless AstroDMx Capture is being used simply to stream video for outreach purposes, and an occasional snapshot is required from the session. The ability to capture individual images is of more importance for microscopy, and to some extent, visually monitored cameras.
AstroDmx Capture for Linux Streaming video from a nest box camera with no camera controls. The software controls are turned off
AstroDMx Capture for Linux streaming video from a nest box camera with no camera controls. The software controls are enabled and adjustments have been made to reveal more of the interior of the nest box.
When the Snapshot button is clicked, a snapshot folder is created in the AstroDMx Capture Data folder and an uncompressed Tiff file is saved. The user should select ‘RAW8’ or RAW16 when connecting the camera rather than RGB, if a colour camera is being used. This will ensure that a very high-quality debayering algorithm is applied to the captured image that is superior to the one supplied in the SDK for the RGB selection. If a monochrome camera is being used, then selecting ‘MONO 8’ or ‘MONO 16’ will, of course, result in an uncompressed greyscale Tiff being saved. The time-stamped Tiff image is saved in the snapshot folder. Immediately to the right of the Snapshot button is a small button that if clicked, allows for the naming of the images to be captured by Snapshot. This name does not override the name selected for general imaging, and if the naming button is not used for snapshots, then the image name from the previous regular imaging session will be used, which may not be appropriate. It is therefore recommended that the snapshot naming button be used routinely when capturing snapshots.
Snapshot of the interior of the nestbox.
