Figure 6.5 Variations in the buttons on the lower left aspect of the main window which show up under
various circumstances. The cancel buttons that appear in the main window when in multi-frame averaging
and/or series capture mode.
Left
: Cancel averaging button.
Middle
: Cancel series button. Both these buttons
will appear simultaneously if you are capturing a series of multi-frame averages.
You may need to wait for
the effect of pressing either cancel button to take place because the program only checks the
GUI events infrequently during an image series or during a multi-frame average sequence. So
click once and leave the mouse pointer over the button till the click has been registered (the
button will change appearance).
Right
: A live countdown timer replaces the ‘Save Image’ button label
when you click it if the ‘Delay first capture by (s)’ setting is more than 0. In this case you can abort the count
down (and the capture event) by left clicking (once) on this button while the count down is in progress.
All multi-frame averaging is done in double precision floating point accumulator buffers.
Once all the frames have been accumulated the result is divided by the denominator (the
number of frames accumulated) using a double precision floating point denominator. The
end result is clipped into the 0-255 range for 8 bpp and 24 bpp outputs but it left in its
double precision floating point form for output as raw doubles and FITS.
The corrections mask support (see below) is not used for multi-frame averaging – full
support is used always even if a custom corrections mask has been supplied.
When the program interfaces with the camera stream it has to request a frame from the
camera and then wait for the camera to respond. Sometimes, especially with the higher
resolutions in raw YUYV streaming format, it can take the camera a long time to respond.
The two settings ‘
Grabber timeout (seconds)
’ and ‘
Frame capture (number of
retries)
’ allow you to set how patient the program is in waiting and retrying if the camera
is taking too long to serve up an image. If these values are exceeded without an image
being retrieved from the stream then the program will give up trying and pop up an error
message. All capture events will be terminated (whether a single frame capture, a multi-
frame average or a series capture). So, if you are doing a long series capture or multi
frame averaging – especially with low light level conditions and high resolution frames it
will be best to keep these value high to avoid your process being prematurely terminated.
The ‘
Series (number of images)
’ value is an integer which tells the program to capture
a series of images at set time intervals, automatically, after you first click the ‘Save Image’
OptArc AF51 Camera Page 77 of 99 User Guide v1.02
