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DCAM, GigE Vision) are important to ensure functionality. Third party-software
includes software such as NI LabVIEW™, MATLAB®, and OpenCV. Often,
third-party software is able to run multiple cameras and support multiple
interfaces, but it is ultimately up to the user to ensure functionality.
Camera resolution by pixel size
Pixel Size (μm) 9,9 7,4 5,86 5,5 4,54 3,69 3,45 2,2 1,67
Resolution (lp/mm) 50,5 67,6 85,3 90,9 110,1 135,5 144,9 227,3 299,4
Typical ½ " Sensor (MP) 0,31 0,56 0,89 1,02 1,49 2,26 2,58 6,35 11,02
Typical " Sensor (MP) 0,59 1,06 1,69 1,92 2,82 4,27 4,88 12,00 20,83
In general, there are two choices when it comes to imaging software:
camera-speci c Software Development Kits (SDKs) or third-party software.
SDKs include application programming interfaces with code libraries
for development of user de ned programs, as well as simple image
viewing and acquisition programs that do not require any coding and o er
simple functionality. With third-party software, camera standards (GenICam,
The size of a camera sensor’s active area is important in determining the system’s
Field of View (FOV) and Primary Magni cation (PMAG). Given a xed
magni cation that is determined by the imaging lens, larger sensors yield
greater FOVs. As shown in Figure 1 and in Table 2, there are several standard
area-scan sensor sizes. The nomenclature of these standards dates back to the
Vidicon vacuum tubes used for television broadcast imagers, so it is important
to note that the actual dimensions of the sensors di er. However, most of these
standards maintain a 4:3 (Horizontal:Vertical) dimensional aspect ratio.
One issue that often arises in imaging applications is the ability of
an imaging lens to support certain sensor sizes. If the sensor is too
large for the lens design, the resulting image may appear to fade away
and degrade towards the edges because of vignetting (extinction of
rays which pass through the outer edges of the imaging lens). This is
sometimes referred to as the tunnel e ect, since the edges of the eld
become dark. Smaller sensor sizes do not yield this vignetting issue.
CCD vs. CMOS Sensors
CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide
Semiconductor) are di erent sensor technologies for converting light into
electronic signals. In a CCD, each pixel’s charge is converted to voltage,
bu ered, and transferred through a single node as an analog signal. In a
CMOS sensor, the charge-to-voltage conversion is done at the pixel level.
Historically, this conversion yielded a less uniform output.
New advances in CMOS technology over the last several years have
helped greatly reduce the non-uniformity in low light environments,
and in many applications high-end CMOS sensors can outperform the
comparable CCD. Additionally, CMOS has lower power consumption
than CCD, which makes them useful for any space-constrained application.
Lower-end CMOS sensors with pixels smaller than approximately
3 microns are still outperformed by CCD in terms of image quality. Performance
di erences are highlighted in Table 3.
Powering the Camera
Many camera interfaces allow for power to be supplied to the camera
remotely over the signal cable (such as USB). When this is not the
case, power is commonly supplied either through a Hirose connector
(which also allows for trigger wiring and I/O), or a standard AC/DC
adapter type connection.
Power over Ethernet (PoE)
Currently, power injectors are available that allow, with particular cameras,
the ability to deliver power to the camera over the GigE cable. This can
be important when space restrictions do not allow for the camera to have
its own power supply. In this case, the injector is added somewhere along
the cable line with standard cables running to the camera and computer.
However, not all GigE cameras are PoE compatible.
Laptops and Cameras
Although many digital camera interfaces are accessible to laptop
computers, it is highly recommended to avoid standard laptops for
high-performance and/or high-speed imaging applications. Often, the
data buses on the laptop will not support full transfer speeds and the
resources are not available to take full advantage of high performance
cameras and software. In particular, the ethernet network speed interface
cards standard in most laptops perform at a much lower level
than the PCIe cards available for desktop computers.
5.8 6.4 7.2
3.6 6.0 4.3 7.2 4.8 8.0 5.4 9.0
Figure 1: Sensor Size Dimensions for Standard Camera Sensors. Not to Scale.
Inch ½.5 Inch ⁄.8 Inch Inch
Table 2: Camera Resolution by Pixel Size.
ccd vs. cmos sensors
CCD CMOS CCD CMOS
Pixel Signal: Electron Packet Voltage Uniform: High Moderate
Chip Signal: Analog Digital Resolution: Low-High Low-High
Fill Factor: High Moderate Speed: Moderate-High High
Responsivity: Moderate Moderate-High Power Consumption: Moderate-High Low
Noise Level: Low Low to High Complexity: Low Moderate
Dynamic Range: High Moderate to High Cost: Moderate Low
Table 3: CCD vs. CMOS Sensors.