CCTV cameras use two image sensor types – CMOS and CCD. The basic working principle has been presented in the “Image sensor” section, and one of the common features is that they are both made of pixels. Those single, solid photosensitive elements, symmetrically distributed in a rectangular shape, form the image sensor.
Fig. 1. CMOST type image sensor in APTI-24C2-36W camera with a 2.1 Mpx matrix.
The resolution offered by the camera depends on the size of matrix used. For example, APTI-50V4-5W camera can record images up to 2592x1944 using the image sensors with the matrix size of 5 Mpx (2592*1944 = 5 038 848, i.e. approx. 5 million). Considering the size of the image sensor - 1/1.8 inch and other components, the effect is truly impressive.
The larger the matrix, the better - the image is made of large number of pixels, it is generally larger and has more details. However this is not a rule, since the matrix size is one of many factors that determine the image quality. The size of a single pixel is also important. The larger the size, the more light can reach the pixel and thus the image can maintain high contrast and details in brighter areas. It explains, why lower-megapixel digital cameras can sometimes take better pictures than higher-megapixel cameras. When selecting a camera, we have to realize that the matrix size is not the only factor affecting the image quality