wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

27-2 Industrial Communication Systems
RGB 4:2:2
pixel (0,0) pixel (1,0) pixel (2,0) pixel (3,0) pixel (0,0) pixel (1,0) pixel (2,0) pixel (3,0)
B
B
B
B
V
V
G
G
G
G
U
R
R
R
R
Y
Y
Y
Y U
pixel (0,1) pixel (1,1) pixel (2,1) pixel (3,1) pixel (0,1) pixel (1,1) pixel (2,1) pixel (3,1)
B
B
B
B
V
V
G
G
G
G
U
U
R
R
R
R
Y
Y
Y
Y
pixel (0,2) pixel (1,2) pixel (2,2) pixel (3,3) pixel (0,2) pixel (1,2) pixel (2,2) pixel (3,3)
B
B
B
B
V
V
G
G
G
G
U
U
R
R
R
R
Y
Y
Y
Y
pixel (0,3) pixel (1,3) pixel (2,3) pixel (3,3) pixel (0,3) pixel (1,3) pixel (2,3) pixel (3,3)
B
B
B
B
V
V
G
G
G
G
U
U
R
R
R
R
Y
Y
Y
Y
4:2:0 4:1:1
pixel (0,0) pixel (1,0) pixel (2,0) pixel (3,0) pixel (0,0) pixel (1,0) pixel (2,0) pixel (3,0)
Y
Y
Y
Y
Y
Y
Y
Y
U
UV
UV
pixel (0,1) pixel (1,1) pixel (2,2) pixel (3,1) pixel (0,1) pixel (1,1) pixel (2,1) pixel (3,1)
Y
Y
Y
U
Y
Y
Y
Y
Y
pixel (0,2) pixel (1,2) pixel (2,1) pixel (3,3) pixel (0,2) pixel (1,2) pixel (2,2) pixel (3,3)
Y
Y
Y
Y
U
Y
Y
Y
Y
UV
UV
pixel (0,3) pixel (1,3) pixel (2,3) pixel (3,3) pixel (0,3) pixel (1,3) pixel (2,3) pixel (3,3)
Y
Y
Y
Y
U
Y
Y
Y
Y
V
V
V
V
FIGURE 27.1
Multimedia information.
used in analog signals, has one plane used for luminance (Y or brightness) and the other two used by the
chrominance component (U and V, the information on color). It is known that the human vision system
(HVS) is more sensitive to the quality of the Y plane than the U and V planes, so subsampling is applied
to reduce the amount of information in analog signals and can be seen as a first stage of compression.
The resolution and the fps rate are established by the type of application. Once established, these factors
influence the requirements of the image’s characteristics, the spatial relationship of the equipment
participating in the application, and the implications for the temporal requirements that must be
satisfied. Although there is a wide range of multimedia applications being used in factory automation,
such as virtual manufacturing [WIF01] or online interactive training, we consider [SS07] process
monitoring and control through image processing to be the most relevant. In the case of monitoring
processes, where an application’s temporal requirements are not critical, the sensor and the visualization
node can be in the same machine, in the same plant, or in any part of the world. In the case of automated
control, where applications do have critical temporal requirements, sensor and processing node
are normally in the same machine (personal area network, distances of a few meters), but other solutions
are possible as well. Reductions in costs and the increases in processing capacity are giving rise to a new
generation of intelligent cameras, where capture and image processing are integrated in the same device
(distances in centimeters). On the other hand, this area is beginning to see the influence of the expanding
use of Ethernet to areas outside the office, and this is leading to the use of IP technology in image
transmission over distances of hundreds meters normally, but also over greater distances, when there
are less strict temporal requirements.
In Figure 27.2, the use of different types of communication networks used in multimedia applications
depending on communication distances between sensor and processing node can be seen.
© 2011 by Taylor and Francis Group, LLC