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CCTV images the way they should be seen
To oversee and adjudicate on a series of predefined tests designed to establish if various CCTV cameras, lenses, infrared lights and associated equipment meet the specified performance criteria. Successful equipment may be used in proposed Taipei City street CCTV installations. The tests were designed to establish that the equipment could meet a required standard of image as defined by BS EN 50132-
The test requirement here is principally that of the cameras, lenses and infrared to produce accurate images of people and license plates on cars, helping a CCTV operator to identify from the recorded images.
To train 150 off police personnel in best practice when specifying a requirement for CCTV the “OR” and how to test CCTV systems and understand what a good CCTV image should look like.
A view from our hotel in Taipei City. This souvenir picture demonstrates perfectly, what a CCTV image should not look like.
We were engaged as independent consultants with no financial interest in the final decision as to what equipment would be used or who would install it. From the point of view of the city police they needed assurance that equipment and methods used and the deployment of the chosen equipment would achieve images that conformed to internationally accepted standards and that images produced by the CCTV system would be “Fit for Purpose”
This was for us in some ways a unique experience, as the client had drafted an Operational Requirement “OR” for each identified location type, at each site they understood exactly the type of image they expected the CCTV cameras to produce. They invited a number of equipment suppliers to bring the equipment that they thought suitable to meet the “OR” requirements specified, so that each offering could be tested against the “OR”
Over a two week period we adjudicated at tests designed around the ROTAKIN/DIGIKIN test target as each identified scenario was replicated, to test the ability of a range of cameras, lenses and Infrared lighting setups to meet the “OR” image standard. Only equipment that met the criteria could be used in the installations across the city.
At the conclusion of the testing the equipment that had passed fit for use was signed off by the CCTV IN FOCUS team, Taipei City government officials then witnessed each piece of equipment along with a copy of the test results, sealed in to boxes that were then placed in to a secure storage facility.
Left is the scene at the sign off, present were members of our team, Taipei City police commanders officials from the Taipei City government audit department, senior managers from Chunghwa Telecom who would be responsible for final installation and senior project managers from Parsons Brinckerhoff.
This process removed one variable from the image quality equation. For once the cameras were installed the image quality achieved would be down to camera positioning and scene lighting prevailing at each installation site. Crucially every camera would be subject to testing day and night to ensure that the images to be viewed by human operators met the “OR” and were Fit for Purpose.
We have shown the image on the right to many UK police officers during training courses and been met with scepticism. An image taken from a recording of a night test under infrared lighting, the clarity and sharpness of the image just shows what can be achieved if a camera is set up properly with care using a suitable test target.
Understand the Operational Requirement, select the correct equipment to achieve the image classification required be it (Inspection, Identification, Recognition, Observation, Detection, Monitor) and test the final recorded images to ensure the image is ‘Fit for Purpose’.
After all, the human observer is the final arbiter for an imaging device whose output is intended for human consumption. Therefore the more objective we can be in testing CCTV systems the better the images we need to see will be.