Cheetah Pregius Camera with GigE Vision
®
Interface – User Manual
August 27, 2019
Page
108
of
123
Rev 1.0
5.11 Area of Interest
For some applications, you might not need the entire image, but only a portion of it. To
accommodate this requirement, the Cheetah camera allows you to create one Region of
Interest (ROI), also known as an Area of Interest (AOI).
Horizontal and Vertical Window
Set the starting and ending point for each AOI independently in the horizontal direction
(Horizontal Window) and the vertical direction (Vertical Window) by setting the window (H &
V) offset and (H & V) size. The horizontal dimension is limited to multiples of 8 pixels, and the
vertical dimension is limited to multiples of 2 pixels. In normal operation, the AOI defines the
number of columns and rows output. The maximum horizontal window size (H) and the
vertical window size (V) are determined by the camera’s image full resolution.
Figure 70:
Horizontal and vertical window positioning
For color version with AOI enabled, use an even number for Offset X and Offset Y to achieve
proper color reconstruction and white balance.
Factors Impacting Frame Rate
The camera frame rate depends upon a number of variables including the exposure time,
number of rows and columns in the AOI, and the bandwidth of the output interface.
AOI size:
Camera frame rate increases by decreasing either the number of columns or number
of rows read out. Changing the number of rows read out causes the largest change in frame
rate.
Exposure Time:
In free-running or Fast trigger mode, the camera overlaps the exposure time
and image readout so frame rate has no dependence on exposure time. In Standard trigger
mode, however, the exposure and readout time do not overlap, and long exposure times will
decrease frame rate.
