The Home Office's Scientific Development Branch (HOSDB) has produced CCTV Technical Concepts: A Guide to Achieving an Effective System (93/08), a training DVD which is intended to provide non-technical users and those buying CCTV systems with an outline of the key issues. Lasting 45 minutes, it uses graphics, video and narration to help cover a range of topics including field of view, illumination, compression, frame rate and resolution.
The video had been into a series of a 12 short clips, each of approximately 3-4 minutes. Each clip can be viewed individually below. Click on the topic heading on the right to view that clip.
10. Resolution
The number of pixels used to produce a single image and how this affects image quality and storage requirements.
1. Introduction
Overview of the contents of the DVD.
2. Field of View
The area captured by the camera: examining lenses, camera locations and camera types for various applications.
3. Depth of Field
How to control the region of interest that is in focus in an image: examining lens apertures and lighting conditions.
4. Illumination
How various light sources can affect the resultant image: examining exposure levels and colour reproduction.
5. Dynamic range
Looking at varying lighting conditions and selecting camera positions to minimize their impact on image quality.
6. Shutter Speed
The period of time over which a single image is captured: examining motion blur and light levels.
7. Sensitivity
A camera's ability to produce a useable image in low light conditions, types of camera to optimise for differing conditions.
8. Compression
Data transmission and storage management with respect to quality and bandwidth. Examples of artefacts introduced by compression.
9. Frame Rate
The number of images displayed per second, its impact on storage capacity and bandwidth.
10. Resolution
The number of pixels used to produce a single image and how this affects image quality and storage requirements.
11. Latency
The delays involved in the video distribution chain and how they can affect certain applications of CCTV.
12. Display
Monitor type, size, positioning and distance from the viewer and how they affect the level of viewable detail.