Basics Fundamentals of Industrial Video Cameras

There are many things to consider when looking to purchase a camera for your application.  Besides the physical apsect of the camera, before one can be integrated

Analog Signal vs. Digital Signal

Analog (analoug) can be defined as a signal that varies continuously over time rather than being sent and received in discrete intervals. The word “analog” implies an analogy between cause and effect, voltage in and voltage out, current in and current out, sound in and frequency out.

Analog Video Signals include:

• RS170 Mono (EIA/CCIR)
• Composite (NTSC/PAL)
• S-video, SVHS, YC
• RGB

Digital is a signal that is sent and received in discrete intervals.  It is a way of sending voice, video, or data that reconstructs the signals using binary codes (1s and 0s) for transmission through wire, fiber optic cable, video conference, or over air techniques.

Digital Video Signals include:

• USB
• FireWire (IEEE.1394)
• CameraLink
• Gigabit Ethernet

High Resolution

Camera resolution is measured in the number of TV Lines, the greater the number of TV Lines the more detail the camera is capable of transmitting. Camera resolution is usually measured by mega pixel. 1 Mega pixel (MP) means that there are one million pixels or one million tiny dots that can be one of various colors creating an image. The more mega pixels in an image, usually means a higher quality resolution.

Interlaced Scan versus Progressive Scan

Two common methods for “painting” a video image on an electronic display screen by scanning or displaying each line or row of pixels.

Interlaced Scan, used in traditional television systems, uses two fields to create a frame. One field contains all the odd lines in the image, the other contains all the even lines of the image, they are drawn alternatively.

Also known as non-interlaced scanning, progressive scan is a method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence rather then alternating even and odd lines like Interlaced.

Monochrome Cameras (B/W) versus Color Cameras

Monochrome is the brightness (luma) portion of a video signal without the color information.  Monochrome is also known as “black and white”, and is what used to predate the color television.

Monochrome Cameras typically have a higher image resolution than colour cameras. In low light conditions a monochrome camera will produce better results. In addition, Colour Cameras are not sensitive to Infrared Light.

Back Light Compensation

For the adjustment of exposure to prevent the subject from turning out too dark when light is coming from behind it. Many cameras are now equipped with a Smart Control which automatically adjust to the level of background light. This enables the camera to pick-up detail which would otherwise be missed.

1/2″ or 1/3″ Format

1/3″ and 1/2″ refers to the size of the imaging area of the CCD or CMOS sensor in the camera. Generally speaking the greater the sensor area, the higher the resolution of the camera. Although more recently high performance 1/3″ CCD imagers have improved in resolution considerably.

Sensitivity

The sensitivity of a camera is typically expressed in either the number of photons or in a measure of photon flux which can be related to human observations. This sensitivity is measured by the minimum amount of light (lux) required to produce a picture. A Lux is a measure of illumination which has a value of 1 lumen per square meter. The Lumen is a photometric equivalent of a watt which is weighted to match the eye response of the “standard observer”

Choosing a more sensitive camera will improve picture clarity.

MAJOR INDUSTRIAL CAMERA MANUFACTURERS INCLUDE:

• AEGIS
• CANON
  • Pan/Tilt/Zoom (PTZ)
  • Network Video/IP Cameras
  • Software
    
• CIS AMERICAS
  • Gigabit Ethernet (GigE)
  • Machine Vision (MV)
    
  • Analog
  • CameraLink (CL)
    
  • Power over CameraLink (PoCL)
  • Monochrome (B/W)
  • Color
    
• ELMO CAMERAS
• FOCULUS
  • S-Series
  • T-Series
  • Foculus
    
• GENWAC/WATEC
  • Color
  • Monochrome
  • Dome
  • 24 Hour
    
  • Power Supplies
  • Cables/Connectors/Accessories
    
• HITACHI
  • FireWire
  • Power over CameraLink (CL)
  • Progressive Scan
  • Interlaced Scan
    
• JAI PULNIX
  
• LUMENERA
• PIXELINK
  • Machine Vision
  • Microscopy
  • OEM Imaging Modules
    • FireWire
    • Gigabit Ethernet
    • USB
      
• QWONN
  
• SENTECH
  • Interlaced
  • Progressive
  • Digital
    
• SONY
  • Security
    
    • Fixed
    • Mini Dome
    • Network/IP
    • Video Recorders
    • Servers
    • Monitors
    • Accessories
  • Smart Cameras
  • FireWire
  • 3 Chip Color
  • Color
  • CameraLink
  • Pan/Tilt/Zoom (P/T/Z)
• TOSHIBA AMERICA
• TOSHIBA-TELI
• UEYE CAMERAS
  

Gigabit Ethernet (GigE) vs. FireWire® (IEEE1394). Do you know the difference?

With today’s abundance of connectivity options available for industrial vision camera applications, users are given the ability to pick and choose the right combination of bandwidth, transmission length, data integrity, and customization for their industrial camera application. When looking specifically at FireWire® IEEE-1394 and GigE, these industrial camera technologies are used in a variety of applications including: Machine Vision, Industrial Inspection, Food Processing, Surveillance, Medical (Microscopy), Bioscience, Military, Automotive, Metrology, Traffic and more.

FireWire® or IEEE-1394 as it is officially called, is a high-bandwidth interface for computers, peripherals, and consumer electronics products. FireWire® is based on a serial bus architecture similar to USB and is typically used to network digital video cameras with computers using specialty cables. The IEEE-1394 technology was created in the late 1980s as a “digital technology designed to satisfy the ever-increasing demand for communications bandwidth for video. It was also designed to simplify and reduce the number of cables and connectors between devices.” (Hardin 2007)

There are two FireWire® versions available, the IEEE1394.a and IEEE1394.b (unveiled October 2004). The difference between the two is that the newer 1394.b offers 800 Mbps whereas its predecessor the 1394a offers 480 Mbps. This increase in bandwidth makes FireWire® IEEE1394.b a close competitor of Gigabit Ethernet (GigE) which offers 1000 Mbps.

Gigabit Ethernet, also referred to as GigE or GigE Vision, is an industrial camera interface standard developed using the Gigabit Ethernet communication protocol. GigE is the first standard to allow fast transfers (1000 Mbps) of data using standard low cost cables over long lengths of up to 100 meters. An industrial GigE camera ultimately gives users increased data transfer speeds and cable lengths compared to FireWire®.

When comparing the two for a particular application, the industrial FireWire® camera is usually a better choice for most Machine Vision applications due in part to the high degree of standardization in the hardware, the software interface, the computer interface, and the lower costs.

When using industrial FireWire® cameras, users find that:

• Cables are less expensive (they can be obtained from a local computer retailer),
• The standardized software interface for industrial cameras (DCAM or IIDC) offers the ability for any compliant camera to be operated by any compliant driver,
• There are minimal framegrabber costs or connectivity issues since many computers are now including built-in FireWire® ports,
• PCI or Cardbus FireWire® interface can be purchased for less than a hundred dollars at your local computer retailer if your computer does not have a built in FireWire® port,
• The software offerings and maturity of the technology’s standardization also makes FireWire® IEEE1394 a good long-term investment in a technology future for your application.

GigE does offer some attractive advantages over FireWire®:

• Cable lengths are available up to 100 meters long (compared to FireWire®’s 5 meters),
• Faster transfer speed (1000 Mbps),
• Provides a truly plug and play interface standard,
• Is slowly becoming the dominant Machine Vision interface (due to increased speed and cable length) as technology progresses.

Now that we have flooded you, our dear reader, with a plethora of information the question still remains, what is best for you and your industrial machine vision application?

At this point there appears to be little advantage in going with the GigE Vision over FireWire® because it is still a new technology that hasn’t found its niche in the marketplace quite yet. It is, however, a great time to look at putting yourself into a position to be an “early adaptor” for this new technology because the day will come when GigE becomes the standard technology for industrial vision applications. To test and implement a new technology typically takes about 3-6 months and those who are at the front of this technology transition will be the ones to benefit as those who chose to wait find themselves having to play “catch up”.

Among the manufacturers currently offering FireWire® and GigE industrial cameras are; Toshiba-Teli with their GiantDragon® GigE and FireDragon® 1394b series, PixeLINK’s FireWire® 1394.a and GigE (coming in January 08) lines, Sony Electronics, Inc. VIP with their Firewire®, IEEE1394.b line, Hitachi Kokusai’s Firewire® 1394.b line and the Foculus FireWire® 1394.a line. Pixelink and Foculus offer capture control display software with their cameras and SDK (Software Developers Kits) for a reasonable fee. Toshiba-Teli offers both capture, control, display software and an SDK at no cost.

(2007) Aegis Electronic Group, Inc.
www.aegis-elec.com

(2007) Hardin, Winn. Digital Camera Network Varieties Solve Complex Application Needs. Retrieved January 16, 2008 from
http://www.machinevisiononline.org/public/articles/details.cfm?id=315