User`s guide

6 Working with Acquired Image Data
To see an example, see “Example: Determining the Frame Delay D uration”
on page 6-22.
Getting the Absolute Acquisition Time
When you use the getd ata function, you can optionally specify three return
values. The firs t contains the image data, the second contains a vector of
relative acquisition times, and the third is an array of structures where each
structure contains metadata associated with a particular frame.
[data time meta ] = getdata(v id);
Each structure in the array contains the following four fields. The AbsTime
field contains the absolute time the frame was acquired. You can also retrieve
this metadata by using event callbacks. See “Retrieving E vent Information”
on page 7-7 for more information.
Frame Metadata
Field Name Description
AbsTime
Absolute time the frame was a cquired, returned in
MATLAB
clock format
[year month day hour minut e seconds]
FrameNumber
Frame number relative to when the object was started
RelativeFrame
Frame number relative to trigger execution
TriggerIndex
Trigger the event is associated with. For example, when
the object starts, the associated trigger is 0. Upon stop, it
is equivalent to the
TriggersExecuted property.
Example: Determining the Frame Delay Duration
To illustrate, this example calculates the d uration of the delay specified by the
TriggerFrameDelay property.
1 Create an im age acquisition object — Th i s example creates a video
input object for a Data Translation image acquisition device using the
default video format. To run this example on your system, use the
6-22