Useful Information
- ♦ Application
- ♦ Cameras
- ♦ Lenses
- ♦ Light & CCTV
- ♦ Number Plate Recognition
- ♦ Thermal Imaging
- ♦ Housings
- ♦ Digital Images
- ♦ Digital Technology & Recording
- ♦ Video Compression
- ♦ Infrared
- ♦ IR & LED Lighting
- ♦ IP CCTV & Technology
- ♦ Monitors
- ♦ Motion Detection
- ♦ Multiplexers
- ♦ PIR Movement Sensor
- ♦ Remote Positioning Devices
- ♦ Video Motion Detection
- ♦ Multiple Screen Display
- ♦ Signal Noise Ratio
- ♦ Survellance Vechicle
- ♦ Three-dimensional (3D) design in CCTV & Security
- ♦ Transmission of Video Signals by Cable
- ♦ Transmission of Video Signals by Remote Methods
- ♦ Transmission of Video Signals by Fibre Optics
- ♦ Video Analysis
- ♦ Wireless CCTV
Digital Images
Most people in the industry and many end users have been waiting with baited breath for what was expected to be a series of draconian regulations imposing severe restrictions on the use of digital recordings. Everyone I spoke to on the subject had their own views of impending doom and enormous increases in costs to comply with these, as then, unpublished papers.
The result? I found the report to be an extremely down-to earth, pragmatic document that deals with the subject realistically. It recognises the inevitability of progress along the digital route and the problems of creating legislation based on technological criteria. The recommendations do come down very heavily on the need for secure audit trails from initial recording to copies produced as evidence.
Although the report does not require forms of encryption, watermarking or other anti-tamper measures it should be remembered that these techniques may well be necessary for other security requirements. The report deals with digital images as evidence only.
There is one great difference between analogue and digital recording. If a copy is made from a tape recording, the copy will be of a lessor quality than the original, if further copies were made from copies the results may well be unusable. A digital recording however, consists of a series of binary digits which can be copied an unlimited number of times with no degradation of the images compared to the original. If an 'original' set of images was on a CD for instance and then copied several times, it would be impossible to determine which was the original and which were copies.
When it comes to the criteria of using video images as evidence, the requirements can appear to be something of a minefield. Add the use of digital images to the equation, and question marks start to appear with regularity. Quite often, depending upon whom you are talking to, you will hear a different version of the so-called "digital dilemma" when it comes to using CCTV footage for evidential purposes. However the police and courts are aware of the potential offered by digital surveillance solutions, and do not want to curtail the use of a credible and efficient tool in the fight against crime.
The Police and Scientific Development Branch have published guidelines for the use of digital images as evidence. The guidelines do not specify which compression algorithm or archiving media should be used instead taking the view that final quality and a credible audit trail are more important.An audit trail for digital CCTV is very much the same as one for an analogue system.