For analog systems, this is typically measured in Television Lines (TVL). The higher the resolution, the better the definition and clarity of the picture. The camera "scans" an image in a series of lines running horizontally. Each horizontal line is made up of a number of elements. Once one line is scanned, the second line is scanned, and so on. Resolution is a measure of the quantity of both individual lines and the component elements making up each line. In a CCD camera, resolution has a direct relationship to the number of pixels on the CCD image sensor.
Resolution measures the number of horizontal lines a camera uses to produce an image. Horizontal resolution measures the number of elements making up each horizontal line. Vertical and horizontal resolutions typically yield a 3:4 ratio relationship (e.g., 600 vertical lines to 800 elements in each line). CCTV camera resolution is usually in the 380 to 540 TVL range. The higher the camera's resolution, the more detail visible (because the lines are closer together and there are more elements in each line). Lower-resolution cameras produce images with less detail.
Other Important Factors
In addition to the primary considerations when selecting a camera, there are several other factors that affect image quality. These include:
- Signal-to-noise ratio
- Automatic gain control
- Automatic shutter
- Backlight compensation
- Manual and electronic adjustments
- Advanced Digital Signal Processing (DSP)
