In August the Home Office’s Centre for Applied Science and Technology (CAST) published updated information on Testing CCTV Image Quality.
CAST has developed a range of tests to assist system installers and owners to robustly assess the performance of their CCTV systems. The tests are designed to be simple to use and produce results that are easy for a non-technical person to understand. The test system helps with common problems like video compression, changeable viewing resolution and variable transmission bit rate/bandwidth, which can all result in the unpredictable quality of digital CCTV images.
The kit is a set of test images and instructions about how to produce and use them. It includes tests for human identification, vehicle registration number legibility, colour rendition and resolution.
Human identification test
The purpose of the test is to help system commissioners and auditors to demonstrate the CCTV system under review is capable of providing images that can be identified. It consists of 12 human faces from which a random selection is presented to the camera at an appropriate distance. An operator attempts to match the presented face to a reference list. The operator’s accuracy is then scored and used to evaluate the capability of the CCTV system to record identifiable images at that distance.
Vehicle registration number (VRN) legibility test
The purpose of this test is to evaluate whether a CCTV system can provide images suitable for reading a VRN. The test kit specifies nine segments of VRN characters. A random selection of those segments is shown to the camera at an appropriate distance. An operator attempts to match the presented VRN to a reference list and their accuracy is scored.
Colour rendition test
The test will help to establish whether a CCTV system can provide images with reasonably accurate colour information. The test kit includes a basic colour chart, which is presented towards the camera at a suitable distance. The operator can then verify the level of match between the colours on a reference chart and the colours seen through the imaging system.
Other test targets included in the system are A3-size versions of the legacy Rotakin test pattern, which allows system testers to use the updated guidance and methods to establish system acuity.
The test kits can be obtained via the Home Office website at gov.uk