8.Features
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch 124
Each pixel is the same as BayerGB8, the difference is that each pixel is made up of two bytes, the first
byte is the low 8 bits of the pixel value, and the second byte is the high 8 bits of the pixel value.
8.3.4.
ROI
By setting the ROI of the image, the camera can transmit the specific region of the image, and the output
region's parameters include OffsetX, OffsetY, width and height of the output image. The camera only reads
the image data from the sensor's designated region to the memory, and transfer it to the host, and the
other regions' image of the sensor will be discarded.
By default, the image ROI of the camera is the full resolution region of the sensor. By changing the OffsetX,
OffsetY, width and height, the location and size of the image ROI can be changed. The OffsetX refers to
the starting column of the ROI, and the OffsetY refers to the starting row of the ROI. Among them, the step
of OffsetX and width vary from one camera to another, and the step of OffsetY and height is 2.
The coordinates of the ROI of the image are defined the 0
th
raw and 0
th
column as the origin of the upper
left corner of the sensor. As shown in the figure, the OffsetX of the ROI is 4, the OffsetY is 4, the height is
8 and the width is 12.
0
0
1
2
3
4
5
6
7
8
9
10
11
0
1
2
3
4
5
6
7
Raw
8
9
10
11
12
12
13
14
15
16
17
18
19
20
21
22
Height
OffsetY
OffsetX
Width
ROI
Column
Figure 8-40 ROI
When reducing the height of the ROI, the maximum frame rate of the camera will be raised. Please refer
to section 8.5.1 for specific effects on the acquisition frame rate.
8.3.5.
Auto Exposure/Auto Gain
ROI Setting of Auto Exposure/ Auto Gain
For Auto Exposure and Auto Gain, you can specify a portion of the sensor array and only the pixel data
from the specified portion will be used for auto function control.
AAROI is defined by the following way:
