An update to this article is available!
This is the first release of the YAACA Linux application. It’s an application written and tested on the ZWO ASI120MC astronomical color camera. I written this application to be able to test all the features of the camera and, of course, to take some cool astronomical pictures. It was developed and tested on Debian 6.0 Squeeze and depends on GTK2. It’s rather simple and should run on most recent Linux systems. You can download the source code and an executable compiled on 32-bit Debian 6.0 Squeeze. Of course you will need the ZWO SDK for compiling and at least the libASICamera.so somewhere in your library path to run the executable. They can be get from the ZWO user group forum (you have to register to have access to the Linux beta SDK).
As you can see the application is quite simple and exposes all the controls of the camera. On the left you have the current captured image. Please note that this image is redrawn on a best-effort basis, the priority is to save the acquired frames to disk. yaaca works with 2 threads, one doing the capture and saving to disk, the other drawing to screen and updating the UI. It will work best on a two or more core system.
On the right you have some output from the camera (name, temperature and number of dropped frames). Below there are controls, they are the same from the SDK, so refer to it for the precise meaning. Exposure is in microseconds for example, others are plain numbers. When you change resolution the start x and y are changed so the ROI (region of interest) is centered on the cross-hair. Some controls have a check-box on their right. If you check it, auto-mode is enabled for that control. On start-up the default value from the driver is read and used.
You can select 4 different formats. RGB24 and Y8 are quite easy to understand. When you select RAW8 or RAW16 a very stupid debayerinng is done on screen (with no gamma correction) but the acquired frame is saved raw (8 or 16 bit per pixel) as a gray scale image. This is of course so one can have maximum flexibility when doing dark subtraction, stacking, deconvolution, etc.
Below you can set the directory where frames are captured (one frame per file) when you check the capture check-box. Each frame is saved with a file-name timestamp-format-gain-exposure. You can save in PNG (both compressed or uncompressed) or PBM (it will be PPM for RGB24 or PGM otherwise). Please note than only saving in PBM doesn’t lose frames on my quite old dual-core laptop I use for astronomy.
Next there is the control of the ST4 port. The box in the center selects the duration (in milliseconds) of the pulse tou give in one of the four directions.
Bellow you can find the coordinates of the cursor/cross-hair and you can enable a zoom on the cursor point (enter the zoom factor, 0 is off). This is useful for focusing. I’m looking forward to implement a better evaluation of image sharpness for good focusing.
Last but not least there is the histogram. You can enable it and select the minimal and maximal value to be displayed for the image (the used part of the histogram is colored red). This is of course useful to stretch contrast, but perhaps it’s better to tune gain and exposure to use all the dynamic of the sensor.