Cheetah Python Camera with USB3 Interface
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User Manual
December 5, 2017
Page
64
of
78
Rev 1.0
Figure 35: Horizontal and vertical window positioning.
Note:
For color version use with AOI enabled, use an even number for Offset X and Offset
Y to achieve proper color reconstruction and white balance.
5.3.3 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, the amount of decimation within the image, and
the bandwidth of the output interface.
AOI size:
Camera frame rate increases by decreasing either the number of columns or
number of rows to read out. Decreasing the number of rows to read out causes the
largest increase in frame rate.
Exposure Time:
In free-running mode, the camera overlaps the exposure time and image
readout. In trigger mode, the exposure and readout time do not overlap, and long
exposure times will decrease frame rate.
Decimation:
The camera supports both subsampling and pixel averaging to reduce the
output resolution. Subsampling and pixel averaging increase the sensor frame rate.
However, subsampling decimation offers the largest frame rate improvement by reducing
the number of rows and columns read out from the image sensor. Subsampling and pixel
averaging decimation provide about a 2x to 3x increase in frame rate.
Output Interface Bandwidth:
The bandwidth of the output interface can impact the
maximum achievable frame rate. For example, the USB3 compatible interface bandwidth
of approximately 3.0 Gbps limits the frame rate.
5.3.3.1 AOI Frame Rate Examples
The table below provides frame rate examples for various AOIs using USB3 output. The
USB3 compatible interface hardware and drivers speed impact results, and results may
vary. The camera calculates and displays the actual frame rate at any horizontal and
vertical window selection.
The following table provides examples of C5180 frame rate performance at full resolution
and within selected AOIs,
