Industry News
Trends in performance surveillance: Right Before Our Eyes
  Date:2010-3-16   Browse: 1223
The days of forensic experts hunting through hours of hazy video footage with poor color reproduction, blurred motion and insufficient detail are coming to an end.
It won`t be long before we all benefit from intelligent performance surveillance systems that detect far more than the human-eye.  Improvements in both surveillance systems and back end intelligent analysis software have evolved to the point where intelligent performance surveillance systems are not just possible, but also practical. This article will explore recent advances in surveillance systems and describe how improved image quality enables intelligent performance surveillance.
Prior to the early 80’s when VCRs took over the surveillance industry, most banking establishments were equipped with Friscoe Bay type 35mm film cameras that were triggered by a teller during a robbery.  After the incident, the police would recover the film, have it developed, and then they would have high quality 8 X 10 photographs of their suspects.  Although the image quality was excellent, the main problem with using 35mm film was that it was time consuming to develop the negatives, and print the images, which is why the industry moved to video cameras and VCRs.
Soon after, time lapse VCRs were introduced.  By slowing the tape in the VCR cassette, less frames per second were recorded, but recordings could span up to 40 days (960 hrs).  One of the problems with Time Lapse VCRs is that the VHS format could only record a maximum of 280 lines of resolution and could only take one video input.  To record more than one camera to a VHS tape, multiplex coder/decoders and video switchers were then used to increase the amount of cameras on one video tape.  This further reduced the amount and quality of images recorded by the time lapse recorder.
In the late 1990’s, the security industry started deploying Digital Video Recorders (DVRs) which took analogue camera inputs and recorded the images using lossy compression onto a hard disk.  This approach to storing surveillance footage was now taking an already bad image and making it worse.  DVR manufacturers extolled the virtues of their ‘digital’ systems advertising large compression ratios and small file size advertise file sizes down to 2.2Kb, however, if a normal video image has a digital matrix of 720 X 486 pixels,  the uncompressed storage of this full image would normally be around 1Mb in size which is 1,000Kb.  So the following question must be raised.  Where is the 998Kb of data that was discarded in the ‘Lossy’ compression recordings?  In spite of the poor image quality DVRs offered, the security industry quickly adopted them due to the convenient features they offered that were not possible on tape-based systems such as easy searching and scheduling.  
By early 2000, image quality in surveillance systems was getting so poor, that the Scientific Working Group on Imaging Technology (SWGIT) collaborated with other scientific working groups to address imaging concerns raised by law enforcement officials and security professionals created by the proliferation of poor quality CCTV systems.   In 2004 SWGIT released “Recommendations and Guidelines for Using Closed-Circuit Television Security Systems in Commercial Institutions”.  These guidelines are instrumental in addressing the concerns of law enforcement agencies and security professionals relating to the use of CCTV systems.  A copy of these guidelines can be obtained from section 4 of the International Association for Identification website at: per image.  Manufacturers of DVRs
To improve the image quality to the level required for security professionals and law enforcement agencies, the industry has had to completely rethink how it engineers surveillance systems.  As our knowledge of imaging, digital transmission, storage and viewing technologies increases, we have taken great strides towards delivering the promise of Intelligent Performance Surveillance.  The biggest technical improvements to date have been on the front end where almost every aspect of image gathering has improved.  A few of the most important developments are detailed below.
Today, for the first time, it is feasible to deploy multi-megapixel cameras that use progressive scan scientific-grade CCD sensors and that deliver true 14-bit dynamic range up to 1,100nm.  Extremely sensitive across the entire visible spectrum and into near infrared wavelengths, the latest surveillance cameras engineered with scientific grade sensors see beyond what the human eye can see.  The human eye can produce about 8-bit dynamic range and sees only to 700nm, so performance surveillance cameras see well beyond human vision (they can actually see 64 times more dynamic range) and are far more sensitive than the best NTSC-based traditional cameras which provide about 8-bit dynamic range.
In addition, scientific-grade sensors have higher Quantum Efficiencies (QE) than their consumer-grade counterparts.  On average consumer-grade sensors found in typical surveillance system have a QE of about 15% while scientific-grade sensors have a QE of up to 60%.  This allows scientific sensors to capture up to 3 times more information than conventional surveillance cameras that use consumer-grade sensors.  This new generation of surveillance cameras can generate images with resolutions of up to 11 megapixels.  This level of detail permits the use of digital Pan/Tilt/Zoom on recorded footage to extract image details after an incident has occurred which is impossible to do with conventional PTZ systems
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