Doktor Jons Guide to the "Use and Application of CCTV"
- This page is part of the "TRUSTED" CCTV Improvement Section -

- A Basic TRUSTED Assessment -

How can you tell if your Video Surveillance System is 'TRUSTED'^©
 

Whilst the "TRUSTED"^© campaign is about raising awareness of how to improve the quality of images and recordings, it is vitally important that CCTV users have a relatively simple way of measuring their systems effectiveness for identifying and recording defined targets

To carry out a ‘basic’ TRUSTED^© Assessment, there are four key areas to review:-

The Cameras, Monitoring Equipment, the Recording System, and Legal Compliance.

A basic evaluation is being developed by Doktor Jon to allow inexperienced end users the opportunity to review and gauge how well their system is performing, and to help identify key areas that may easily be improved. This brief section will explain a little more about how the appraisal will work ...

Camera Assessment

Each camera in the system will need to be evaluated to see how well it is performing in terms of display and recording. Whilst this analysis relates specifically to it’s role for Incident Monitoring and consequently Evidential Recording, it does not at all relate to it’s possible use for either Site Management or Deterrence, both of which are really outside of the scope of this ‘basic’ TRUSTED^© assessment.

It's worth briefly restating that in practice, the roles of Site Management and Deterrence actually have no impact on the systems suitability for gathering and displaying evidential quality images, and so can safely be disregarded for now.

Now if you want to evaluate an individual camera, you have to display it (unprocessed) directly onto a suitable monitor, which for the purposes of this basic evaluation, will almost certainly be the main display screen.

Just for your information, with a more detailed professional assessment, this would normally require picture analysis to be done in two stages. Firstly with a high quality test monitor connected directly to the camera using a short signal lead, this makes it easy to gauge the overall quality of the image coming straight out of the camera.
In the second stage, the cameras performance would then be compared against the perceived quality of image at the monitoring end, so that any inadequacies in the transmission system can be easily identified, and hopefully remedied - in practice, this evaluation can be achieved with or without the use of technical measuring equipment, although it does require some degree of technical knowledge to identify any shortcomings.

For the purposes of this basic assessment, you need to define a specific target recognition area in the picture; now this could be part of the image or indeed everything shown on the screen - this is the area where your cameras should be optimised for target recognition. To carry out a simple evaluation of whether a camera is performing correctly in terms of its suitability for target identification and evidential recording, there are four basic factors which need to be considered:-

1. PICTURE QUALITY
This will relate to the camera / lens combination being used, how well it has been set up, whether the lighting is adequate and appropriate for the task, and whether the transmission system is performing correctly.

2. TARGET SIZE
In order for a target (for example a person, a face or a vehicle number plate) to be recognisable, it has to be displayed on the screen in sufficient size and clarity to be useful; if it’s too small, then it just won’t do the job.
It’s worth briefly mentioning here that many of the very latest networked “MegaPixel” cameras are quite capable of reproducing good detail from wider angle views, but as these cameras are still relatively new and not widely used, this assessment is not yet intended to take account of their higher level performance.

3. TARGET PRESENTATION
Apart from having a target on screen in sufficient size to be identifiable, it is also vitally important that the target is presented to the camera in such a way that it is recognisable. After all, you could fill the screen with the top of someones head, but it doesn’t mean you can easily identify them from their bald patch! So getting the camera pointing in the right direction, and from the correct position, is far more important than most people understand.

4. TARGET DURATION
Having established that the size and presentation of a target is key to producing a usable image, the final factor is the length of time that the target remains in view of the camera (of course, this relates to the time on screen, with the appropriate sizeing and presentation). This factor is particularly important where for example there are many cameras connected either to an analogue Time Lapse video recorder, basic Digital Video Recorder (DVR) or low bandwidth network.

As an example, if the target only presents itself on screen in an ‘optimised’ position for perhaps two seconds, then that isn’t very useful if the cameras image is only being recorded once every three seconds.

You may have a terrific image of a suspect on screen, but it may never get to be recorded. The object of the exercise is to achieve as many recorded quality images as possible. This same principle could equally apply to modern IP Video or Network connected cameras, where the speed and load on the network (amongst other things) will dictate how many pictures can be transmitted each second.

All the information for testing the cameras performance can be recorded on the simple TRUSTED CCTV System check lists, which will be available shortly.

The next stage of this "TRUSTED"^© Basic CCTV assessment >>

Can you help? ....Subject to feedback, further work will be carried out on developing this ongoing section throughout 2008 and beyond. So if you have any specific requests for more information, comments or suggestions for inclusion in this project, or would just like to offer your support, please don't hesitate to let me know:-

e-mail to: info[at]doktorjon.co.uk

IMPORTANT: No material may be reproduced, copied or redistributed from this site,
without the express written consent of doktorjon.co.uk

All the detailed information on this site is provided in good faith; as such, Doktor Jon does not accept responsibility for any consequential loss, injury or disadvantage resulting from any individual or organisation acting on the details contained herein.

© doktorjon.co.uk 2004 - 2009

Homepage...:...Gateway...:...Technical Gateway....:....Quickfind Index....:....Equipment Directory
Site Index...:...About this site....:....CCTV Helpdesk....:.... The Forum ....:....Contact Doktor Jon