Why are CCTV Images so poor quality?
It is estimated that over 80 percent of crimes caught on CCTV do not result in a prosecution. In a world of modern technology where everyone has a smartphone with a built in camera that takes exceptional pictures, many find it confusing when they see poor quality CCTV Images in the press.
Historically the problem was down to the technology used, first with VCRs with multiplexed images and subsequently with Digital Video Recorders where limited hard drive size was a huge limiting factor. Even with a good quality analogue camera, by the time the image had been compressed to allow up to 16 cameras to record for 31 days, much of the original detail had been lost.
So why are images still so poor in many cases?
In many cases the biggest problem is a lack of storage. As technology has advanced, the cost of the equipment has been reducing and most importantly the cost per gigabyte of storage has come down significantly. The problem is that rather than end users opting for better technology with more storage, in many cases the choice is taken to pay less instead. This means that once again image quality is sacrificed and there is still a big difference between the live and recorded images.
One other issue that has always been a problem is that many cameras are set up to view too large an area. Home office guidelines state that for the standard PAL analogue recording format with no significant compression applied, a person of average height should fill the entire field of view in order to be able to identify them. Rarely is this ever the case.
Nowadays cameras are available with much higher resolutions which means that a much larger area can be viewed from a single camera but care still needs to be taken to ensure there are enough pixels per metre to allow identification of a person or number plate to take place.
Another significant factor that affects CCTV performance is lighting levels. Most CCTV systems are specified during hours of daylight meaning the surveyor cannot truly assess the lighting conditions at night. Although many systems are capable of providing images at low light levels or are supplemented by Infra Red illuminators, the images will be in black and white. Although this is sufficient for live monitoring of an area, it is far from ideal when you are trying to identify an assailant after an incident has occurred.
If you truly want to both deter criminals and capture quality footage during hours of darkness then the advice would be to add white LED lighting into the system design as this will ensure the images captured are in full colour and are far more likely to lead to identification.
There are cameras available that will provide colour images even in dark conditions using proprietary image processing technology and are quite amazing when you see them in action.
Lack of lighting doesn’t just cause problems at night. If a camera is set up to view an entrance where there is the possibility of bright sunlight outside, care must be taken to select the correct camera otherwise the camera iris will close causing the person to look like a silhouette. In this case, a camera with a ‘wide dynamic range’ should be selected to allow it to distinguish details in the dark areas of the image.
How do I get good quality CCTV?
Firstly the operational requirements should be agreed upon, i.e. what are the risks, what are you trying to protect, what should the system do if an incident occurs e.g. allow identification in a certain area/areas and what do the different stakeholders need from the system.
As well as agreeing the areas to be monitored by the CCTV system, the correct resolution for a given field of view also has to be specified correctly. Even if a camera is only to provide a view of a large area for detection purposes (e.g. and overview of a car park), it is still important to site cameras to allow the identification of individuals/vehicles at the entry points. Correct camera and lens selection is critical at this stage.
A full assessment of required lighting levels should also be carried out prior to any decision being made. Ideally lighting should be LED as this is both cheap to run and ideal for CCTV. Where possible, the system should be commissioned at night and optimised for the lighting levels.
Following on from all this the storage supplied should be sufficient to allow for the agreed frame rate and quality so that the resolution from the cameras is not lost. We will be more than happy to help with this so please get in touch.