Night Ccd
The Three Primary Technologies for Night-time Video Surveillance
Introduction
There are lots of challenges in performing video surveillance at night. Selecting the best video cameras for a particular application will depend on the specific requirements that are deemed necessary. For example,
- Are both day and night video operation desired?
- Does the surveillance system need to be covert (so that no visible illumination is used at night)?
- Does the surveillance system need to be undetectable and completely “passive”?
- What is the size and shape of the area to be monitored? How far are objects to be observed?
- Is the goal of the surveillance to detect, recognize or identify objects in the field of view?
The “best” system design for a specific night-time video surveillance system will use one of the three primary night vision technologies: low-light imaging, thermal imaging and near-infrared illumination. In this article, these three technologies are explained and the advantages of each reviewed.
As shown in the figure that can be referenced at link below, each night vision technology exploits a different range of the electromagnetic spectrum. Low-light imaging devices basically work in the visible light range, normally 400-750 nm. Near-infrared illumination operates in the non-visible near-infrared spectrum, wavelengths slightly longer than visible light. Thermal imaging operates in the infrared range of wavelengths, normally 3-5 microns or 8-12 microns.
Electromagnetic Spectrum
The table that can be referenced at the link below summarizes some of the differences in the technologies.
Low-light Imaging Although image intensifiers are the most common night vision technology, they are predominant in portable applications such as night vision photography and night-time electronic news gathering. For video monitoring applications, other technologies exist that produce results that are in many ways superior. Specifically, electronic multiplication CCD detectors, or EMCCD cameras (described below), have become popularized for performing low-light security and surveillance monitoring. Other enhanced CCD cameras including integrating CCD cameras are also available that perform image processing tricks to enhance certain aspects of camera performance at the expense of other performance specifications.
EMCCD Cameras Electron multiplication CCD or EMCCD cameras incorporate a significant advancement to CCD detector technology that results in performance better than intensified CCDs. At the heart of the EMCCD is a highly sensitive CCD detector that has its image signal amplified on the chip while it is still in the charge domain. The multiplication gain (which takes place after photons have been detected in the device’s active area but before one of the detector’s primary noise sources) amplifies signal electrons up to 1000 times so that they may be detected above the CCD output and camera electronics noise.This allows the sensor to operate in real time with sub-electron equivalent readout noise, enabling very dim sources and very dark scenes to be imaged. These sensors maintain full well capacity and high quantum efficiency while minimizing blooming from strong light sources in the object being imaged. As a result, EMCCDs are now preferred in many low-light applications such as night-time surveillance and astronomy. In addition, EMCCDs have the capability to operate across the full range of light levels which results in it’s usefulness for 24-hour surveillance.
Advantages of EMCCD Cameras:
- High sensitivity to low-light
- High spatial resolution & contrast
- No halo from bright sources allowing visible detail in adjacent pixels
- Not susceptible to damage from bright lights
- No scintillation giving improved image quality
- Solid state giving lower lifecycle cost
- Excellent for day and night operation
Integrating CCD Cameras Another method for improving a CCD camera’s sensitivity is to perform averaging to reduce noise either temporally (where sequential video frames are averaged) or spatially (where neighboring pixels are “binned” or added together). By performing special processing of the signal inside the CCD, superior performance over standard CCD cameras can be achieved. Certain CCD cameras have the capability to automatically perform binning (where the signal from adjacent pixels are averaged) and frame averaging (where the pixel signal from sequential video images are averaged) when light levels fall below acceptable values. These image processing techniques decrease noise levels and result in superior low-light performance up to 100 times lower than standard CCDs. However, this technique does have compromised performance. Binning will result in a decrease in resolution. Normally, binning is performed in the vertical dimension first, retaining the level of horizontal resolution normally important when imaging objects at the horizon. Temporal integration causes the apparent sensitivity to still objects increases while moving objects may become blurry.
Thermal Imaging Different from low-light imaging methods of night vision (which require some ambient light in order to produce an image), thermal imaging does not require any ambient light at all. Thermal infrared cameras operate on the principal that all objects emit infrared energy as a function of their temperature. In general, the hotter an object is, the more radiation it emits. An infrared camera is a product that collects the infrared radiation from objects in the field-of-view and creates an electronic image based on the level of radiation detected. Since they do not rely on reflected ambient light, infrared cameras are entirely ambient light-level independent. In addition, they also are able to penetrate obscurants such as smoke, fog and haze. There are two types of thermal imaging detectors: cooled and uncooled. Cooled detector infrared cameras require cryogenic cooling to very cold temperatures (below 200K). Uncooled detector infrared cameras are normally either temperature stabilized (at room temperatures) or entirely unstabilized. Thermal images are normally black and white in nature, where black objects represent cold objects and white objects represent hot objects. Some thermal cameras show images in color. This false color is an excellent way of better distinguishing between objects at different temperatures.
Thermal infrared cameras operate on the principal that all objects emit infrared energy as a function of their temperature.
Cooled-detector Infrared Cameras
Cooled infrared detectors are typically housed in a vacuum-sealed case and cryogenically cooled. The detector designs are similar to other more common imaging detectors and use semiconductor materials. However, it is the effect of absorbed infrared energy that causes changes to detector carrier concentrations which in turn affect the detector’s electrical properties. Cooling the detectors (typically to temperatures below 110 K, a value much lower than the temperature of objects being detected) greatly increases their sensitivity. Without cooling, the detectors would be flooded by their own self-radiation. Materials used for infrared detection include a wide range of narrow gap semiconductor devices, where mercury cadmium telluride (HgCdTe) and indium antimonide (InSb) are the most common. Cameras based on cooled HgCdTe and InSb detectors have similar performance, however HgCdTe detectors are often preferred because they exhibit higher quantum efficiency and wavelength tunability (including performance in shortwave, midwave and longwave bands as well as dual-band).
Advantages of Cooled-detector Infrared Cameras:
- The highest possible thermal sensitivity
- Able to detect people and vehicles at great distances
- Not affected by bright light sources
- Able to perform high speed infrared imaging
- Able to perform multi-spectral infrared imaging
Uncooled-detector Infrared Cameras Unlike the cooled detector cameras described above, uncooled infrared detectors operate at or near room temperature rather than being cooled to extremely low temperatures by bulky and expensive cryogenic coolers. When infrared radiation from night-time scenes are focused onto uncooled detectors, the heat absorbed causes changes to the resistance properties of the detector material. These changes are then compared to baseline values and a thermal image is created. Despite lower sensitivity than realized in cameras using cooled detectors, uncooled detector infrared cameras are smaller, much less costly and have higher operating reliability over time. As a result, these new technology infrared cameras open many viable commercial applications.
Advantages of Uncooled Infrared Cameras:
- Relatively inexpensive compared to other thermal imaging technologies
- High contrast in most night-time scenarios
- Easily detects people and vehicles
- Not affected by bright light sources
- Higher reliability than cooled detector thermal imagers
Near Infrared Illumination A popular and sometimes inexpensive method for performing night vision is by near infrared illumination. In this method, a camera that uses a detector that is sensitive to invisible near infrared radiation is used in conjunction with an infrared illuminator. The Sony Night Shot camcorder popularized this method. Because of the IR sensitivity of the camcorder’s CCD detector and since Sony installed an infrared light source in the camcorder, infrared illumination was available to augment otherwise low-light video scenes and produce reasonable image quality in low-light situations without the use of visible light sources.
The method of near-infrared illumination has been used in a variety of night vision applications including perimeter protection where, by integrating with video motion detection and intelligent scene analysis devices, a reliable low-light video security system can be developed.
Several different near infrared illumination devices are available today, including:
- Filtered incandescent lamps: A standard high power lamp covered by a filter designed to pass the lamp’s near infrared radiation and block the visible.
- LED type illuminators: These illuminators utilize an array of standard infrared emitting LEDs.
- Laser type: The most efficient infrared illuminator, these devices are based on an infrared laser diode that emits near infrared energy.
Near infrared illuminators are typically available in a range of wavelengths (e.g. 730nm, 830nm, 920nm). Providing supplemental infrared illumination of an appropriate wavelength not only eliminates the variability of available ambient light, but also allows the observer to illuminate only specific areas of interest while eliminating shadows and enhancing image contrast. The supplemental near infrared lighting improves the quality of solid state cameras that have the ability to convert near infrared images to visible.
Advantages:
- Lowest cost compared to other night vision technologies.
- Eliminate shadows and reveal identifying lettering, numbers and objects. Can also be used to perform facial identification.
- Able to perform high-speed video capture (such as reading license plates of moving vehicles).
- IR illuminators can see through night-time fog, mist, rain and snowfall as well as windows
- Eliminates the variability of ambient light.
Summary Clearly, the optimal solution for a particular night-time video surveillance application will depend on the requirements for that application. The “best” design will utilize one of the three primary night vision technologies: low-light imaging, thermal imaging and near-infrared illumination.
The table that can be referenced at the link below summarizes some of the differences in the technologies.
The following refer to each capability in the table:
24-hour surveillance - All three technologies permit (to some capacity) 24-hour surveillance.
Detection - Thermal imaging is considered the superior technology when detection is required. Most objects under surveillance, whether they are people or vehicles in motion, have thermal signatures that are distinct from the background. As a result, these objects normally show high contrast with respect to the background and are easy to spot.
Recognition/identification - For recognition/identification applications, thermal imaging is not the preferred technology since thermal signatures are in many cases difficult to identify and distinguish. Low-light imaging is best since it generates an amplified version of the visible light signature. Near-infrared illumination is also useful, but it is important to realize that reflectivity in this spectral range may differ from the reflectivity in the visible range. As a result, identifying marks on vehicles may be difficult to read, hair color and complexion will also differ when imaging in these wavelengths.
Passive operation - Low-light and thermal imaging are both passive technologies since neither surveillance method is easily detected. Near-infrared illumination, on the other hand, is considered active since it emits a beam of near infrared light that can be detected with other near-infrared sensitive devices.
Ambient light level independent - Thermal imaging and near infrared illumination are somewhat light level independent. The presence of sunlight will cause solar heating that will impact thermal images, creating shadows and hot spots that are different than night-time. Near-infrared systems are often considered independent of ambient light since they emit their own illumination, but quite often these systems take advantage of the sun’s near-infrared radiation and may disable the separate illuminators. Image quality for low-light imagers will depend greatly on the ambient conditions.
For an online version of this article with all referenced illustrations, please click here.
About the Author
For more comprehensive White Papers visit our online Knowledge Center.
www.electrophysics.com/night-vision
Electrophysics – Night Vision for Digital Photo/Video
Groupe Sofradir
373 Route 46, Fairfield, NJ 07004
Phone: 973-882-0211
Fax: 973-882-0997
www.electrophysics.com
© 2009 Sofradir EC, Inc. All rights reserved.
An ISO 9001:2000 Certified Company UKAS #7096 – ANAB #A060693
Cambodian Community Night Dance Party Part 1
|
|
New 1/3 SONY CCD 420TVL Night Network Outdoor IP Camera $141.55 |
|
|
6 LED Spy night Camcorder Surveillance Camera CCD CCTV $0.94 |
|
|
Sharp Color CCD Camera Backup Car Rearview IR Night Cam $24.00 |
|
|
10Pcs Sony 1/3 CCD 20M 35IR LED NIGHT COLOR CAMERA CCTV $241.42 |
|
|
1/4 Sharp Chip 42Led IR Day&Night CCTV Wired CCD Camera $26.42 |
|
|
Wide angle Night IR CCD home security system camera 1ns $72.99 |
|
|
Sony 1/4 CCD 18M 24 IR LED NIGHT COLOR CAMERA NTSC * $18.00 |
|
|
Double Sony CCD 480/600 Line Day/Night External Camera $252.35 |
|
|
Day Night Array IR LED Illuminator Sony CCD CCTV Camera $96.89 |
|
|
550TVL Sony 1/3″ SuperHad II CCD IR night vision Camera $90.00 |
|
|
550TVL Sony 1/3″ SuperHad II CCD IR night vision Camera $96.57 |
|
|
Day Night Security Camera CCTV SONY CCD Color video boa $109.09 |
|
|
550TVL Sony 1/3″ SuperHad II CCD IR night vision Camera $97.03 |
|
|
Outdoor Dome Color CCD IR Day Night Security Camera bdq $44.99 |
|
|
CCD NIGHT VISION A/V WIDE ANGLE REAR VIEW BACKUP CAMERA $109.99 |
|
|
outdoor security camera IR day night 1/3 SONY CCD buh $74.99 |
|
|
SONY CCD 540TVL 40M IR Night Waterproof Outdoor Camera $86.99 |
|
|
IP IR 50M Camera sony ccd CCTV SD PDA night vision US $248.40 |
|
|
420L Sharp SUPER HAD CCD IR Night Vision Dome Camera $0.99 |
|
|
NIGHT VISION OUTDOOR CAMERA 1/3″ SONY CCD CCTV COLOR N8 $42.98 |
|
|
4x NIGHT VISION OUTDOOR CAMERA 1/3″ SONY CCD COLOR N8B $168.68 |
|
|
Security CCTV Dome Camera CCD 420TVL 42LED Night Vision $34.00 |
|
|
Waterproof Surveillance CCD Day&Night Camera IR LED 30M $74.09 |
|
|
P160 Outdoor Day Night Sony 1/3″ CCD CCTV Camera $47.99 |
|
|
SECURITY OUTDOOR SONY CCD COLOR CAMERA NIGHT VISION N7 $42.98 |
|
|
36LED 1/3” SONY CCD DAY/NIGHT WATERPROOF CCTV CAMERA 7 $42.98 |
|
|
Security CCTV CCD Waterproof Camera 420TVL Day&Night $44.00 |
|
|
48IR Night Vision Sharp1/3 CCD Weatherproof Camera 420L $0.99 |
|
|
New 1/3″ CCD IR Night Vision Security CCTV Dome Camera $38.00 |
|
|
Security CCTV Camera Day&Night CCD 420TVL Weatherproof $47.00 |
|
|
1/3″ CCD Security CCTV Dome Camera 24IR LED Day&Night $53.00 |
|
|
480TVL HAD CCD 27X Digital Day&Night CCTV Zoom Camera $77.60 |
|
|
Outdoor Waterproof CCD Color Camera 6.0mm IR Night 20M $36.99 |
|
|
1/3″ Sony CCD day&night CCTV waterproof IR Camera SY1 $45.00 |
|
|
SECURITY OUTDOOR SONY CCD COLOR CAMERA NIGHT VISION N7 $39.88 |
|
|
Car Rear View Backup Reversing Night Vision CCD Camera $41.13 |
|
|
Dome Vandal Proof Night Vision SONY Security Camera CCD $99.99 |
|
|
Wide Angle IR Day Night Audio Video SONY CCD camera b43 $79.09 |
|
|
SONY 540TVL CCD Day Night Outdoor CCTV Security Camera $109.00 |
|
|
1/3” SONY Dome CCD CCTV DAY/NIGHT security camera N6 $32.88 |
|
|
★bullet IR camera day night color 30 LED video CCTV CCD $0.99 |
|
|
★bullet IR camera day night color 30 LED video CCTV CCD $0.93 |
|
|
1/3″ Sharp CCD Night Vision Infrared CCTV Camera 420TVL $32.98 |
|
|
24LED IR Night Vision Dome Camera 1/3″ CCD SONY 420TVL $35.98 |
|
|
Lot of 2 Movable Day/Night Dome Sharp CCD CCTV Camera m $73.78 |
|
|
Sony CCD Waterproof 48 IR CCTV Camera Night Vision N8 $42.88 |
|
|
540TVL Sony CCD Outdoor Car License Camera IR Night CE $199.49 |
|
|
★bullet IR camera day night color 30 LED video CCTV CCD $0.93 |
|
|
1/3” SONY Dome CCD CCTV DAY/NIGHT security camera N6 $32.88 |
|
|
1/3” SONY IR CCD Dome Night vision Security Camera N6 $32.88 |
|
|
4 Pcs Sony1/3 CCD 25M 35 LED Night Camera For CCTV DVR $104.77 |
|
|
4 Security Day Night Waterproof Sony CCD CCTV Cameras $259.00 |
|
|
1/4″ 420TVL SHARP CCD CCTV Camera Night Vision Outdoor $19.99 |
|
|
6 LED Spy night Camcorder Surveillance Camera CCD CCTV $0.94 |
|
|
1/3″sony 420tvl night/Day Board CCD color cctv camera $30.00 |
|
|
1/3″sony 540tvl night/Day Board CCD color cctv camera $44.00 |
|
|
EXREME 126 Led 24vac Infrared Night Camera Sony 1/3″CCD $159.99 |
|
|
Security CCTV Dome Camera CCD 420TVL 42LED Night Vision $34.00 |
|
|
1/3″ SONY COLOR CCTV CCD Night vision OUTDOOR CAMERA N7 $39.88 |
|
|
Security CCTV CCD Waterproof Camera 420TVL Day&Night $44.00 |
|
|
Night vision OUTDOOR 1/3″ SONY COLOR CCTV CCD CAMERA N7 $39.88 |
|
|
1/3″ Sony CCD Color Camera IR Night Vision Dome Camera $44.99 |
|
|
4pcs 1/4″Sharp CCD Day&Night Color CCTV Dome Camera $128.80 |
|
|
New 1/3″ CCD IR Night Vision Security CCTV Dome Camera $38.00 |
|
|
CCTV 1/3 SONY CCD IR Day/Night Security IR Camera Z28 $39.80 |
|
|
Security CCTV Camera Day&Night CCD 420TVL Weatherproof $47.00 |
|
|
1/3″ CCD Security CCTV Dome Camera 24IR LED Day&Night $53.00 |
|
|
Wireless 12 LED Day-Night CCD Security Camera 18-016N $41.59 |
|
|
Day-Night 12 Infrared CCD Security Spy Camera 18-027N $34.69 |
|
|
Infrared 24 Light Day-Night CCD Security Camera 18-061 $53.19 |
|
|
DAY / NIGHT IR COLOR DOME CCD SURVEILLANCE CAMERA $94.99 |
|
|
Sony Vision Camcorder CCD – TRV37 8mm Night Vision $53.00 |
|
|
Day Night Array IR LED Illuminator Sony CCD CCTV Camera $94.99 |
|
|
450 TVL Sony CCD Color Indoor Camera IR Night Vision $59.84 |
|
|
IR Night Vision CCD Outdoor CCTV Security Camera $57.95 |
|
|
CCTV Security system IR Night Vision Outdoor CCD Camera $65.95 |
|
|
Outdoor Dome Color CCD IR Day Night Security Camera bdq $44.99 |
|
|
SECURITY SHARP COLOR CCD NIGHT VISION DOME CAMERA S05 $34.00 |
|
|
SECURITY SHARP COLOR CCD NIGHT VISION DOME CAMERA S29 $35.00 |
|
|
CCTV Double/Dual Sony CCD 600Line Day/Night Camera S64 $118.00 |
|
|
CCD CCTV Day/Night Waterproof Security IR Color Camera $49.50 |
|
|
Car CCD Color Rear View IR Night Vision Backup Camera $47.49 |
|
|
Swann BullDog CCD Color Camera Night Vision Security $56.05 |
|
|
Night Outdoor Vision Sharp CCD Waterproof CCTV Camera $19.99 |
|
|
NEW 6LED Spy IR Camcorder night vision Camera CCD CCTV $0.94 |
|
|
IR Night Vision Armor Dome Camera, 1/3 SONY CCD, 420TVL $44.88 |
|
|
i-mobile 902 CCD camera cellphone NIGHT CAMERA UNLOCKED $89.99 |
|
|
**VIEW CFH22 DAY/NIGHT CCD CAMERA IN GREAT CONDITION** $39.99 |
|
|
CCD Infrared Night Vision Water Resistant CCTV Camera $35.81 |
|
|
★bullet IR camera day night color 30 LED video CCTV CCD $0.99 |
|
|
Car Rear View Backup IR Night Vision Colour CCD Camera $75.00 |
|
|
Sony Handycam CCD-TRV99 Hi8 Hi-8 Camcorder -Night 0 LUX $86.00 |
|
|
Sony 1/4 CCD 18M 24 IR LED NIGHT COLOR CAMERA NTSC * $18.00 |
|
|
10Pcs Sony 1/3 CCD 20M 35IR LED NIGHT COLOR CAMERA CCTV $245.00 |
|
|
outdoor security cctv camera night vision color CCD bum $299.99 |
|
|
Night Vision video Camera 1/3″ SONY CCD Outdoor LED c37 $79.99 |
|
|
(4) 1/4″ SHARP COLOR CCD 420 TVL NIGHT VISION IR CAMERA $125.00 |
|
|
48IR Night Vision Sharp1/3 CCD Weatherproof Camera 420L $0.99 |
|
|
Long Range Day Night Infrared Sharp 1/3″ Color CCD 480L $0.99 |
|
|
Long Range Day Night Infrared Sharp 1/3″ Color CCD 480L $0.99 |
|
|
London, England (Night Skyline, Door) Art Poster Print – 20×61 $4.46 London, England (Night Skyline, Door) Art Poster Print – 20×61… |
|
|
New Fujifilm 12 Megapixel CCD Digital Camera RED 3x Optical Zoom Picture Stabilization $106.69 Our most popular model…. |
|
|
Starry Night Napkin Set $30.00 Add an elegant touch to your dinner table with this set of richly colored napkins. Crafted of 100% preshrunk cotton — finished with a decorative rolled edge stitch for an arty flair. Generously sized at 17 x 17 inches, machine washable…. |
|
|
Night Dubbin $10.12 2009 set compiled by Dimitri from Paris, arguably the world’s foremost Disco DJ and mixed by the Idjut Boys, kings of the London Nu-Disco scene. The set contains a great mixture of Pop and underground ’80s classics, most of which do not appear on any other compilation out there. Includes cuts from Wham, Electric Dead, Rah Band, D-Train, Raw Silk, Lenny White and many others…. |
|
|
Go West – Dancing on the Couch [Vinyl Lp Record] $14.99 10 Tracks: I Want to Hear It From You, Little Caesar, Masque of Love, From Baltimore to Paris, True Colours, The King Is Dead, Chinese Whispers, Let’s Make A Boat, Crossfire, Dangerous… |
|
|
Silent Night: A Collection of the Best Loved Songs of Christmas $1.99 20 tracks… |
|
|
Defender SN301-8CH-008 8 Channel H.264 Smart DVR Security System with Coaching iMenu and 8 Hi-Res CCD Night Vision Surveillance Cameras (Black) $680.00 This Defender DVR system will work for almost any property because it includes 8 indoor/outdoor night vision cameras. Depending on the size of your business or home, you can mount the cameras at all entrances, in your yard and even inside. Setup is fast and hassle-free because everything you need is included in one simple kit and an interactive coaching menu helps you along the way. Keep a constan… |
|
|
Defender SN502-4CH-002 Feature-Rich 4-Channel H.264 DVR Security System with Smartphone Access and 4 Indoor/Outdoor Hi-Res CCD Night Vision Cameras $449.98 The Defender SN502-4CH is a complete DVR security system that has all the latest features yet is very easy to use. It has been specifically designed for do-it-yourself applications. This kit includes a four channel DVR with built-in hard drive, four indoor/outdoor night vision cameras, and all accessories needed to start monitoring your property immediately. Setup is fast and hassle-free because e… |
|
|
SVAT CV301-8CH-002 Web Ready 8 Channel H.264 500GB HDD DVR Security System with Smart Phone Access and 4 Indoor/Outdoor Hi-Res Night Vision CCD Surveillance Cameras $549.99 The CV301-8CH includes four outdoor night vision cameras and can be expanded to include up to four more. As your business, family or home grows, so can this system. Setup is fast and hassle-free because everything you need is included in one simple kit and an interactive coaching menu helps you along the way. Keep a constant watch of your property and record over a month of video on the DVR’s buil… |
|
|
SVAT CV502-4CH-002 Web Ready 4 Channel H.264 500GB HDD DVR Security System with Smart Phone Access and 4 Indoor/Outdoor Hi-Res Night Vision CCD Surveillance Cameras $899.99 Feature-rich and easy to use, the SVAT CV502-4CH-002 complete DVR security system has been specifically designed with the do-it-yourself consumer in mind. This kit includes a four channel DVR with a built-in 500GB hard drive, four indoor/outdoor hi-res night vision CCD cameras, and all the accessories needed to start monitoring your property immediately. In addition, the interactive coaching menu … |
