Pixel and lens explained in detail

What is a Pixel?

Pixel is an abbreviation for "Picture Element". It is the **smallest unit** that makes up a digital image. You can think of a digital picture as a grid of countless tiny squares, each of which is a pixel. Each pixel carries specific color and brightness information.

The resolution of an image is usually expressed in terms of the width and height of the pixels, such as 1920x1080 pixels. This means that the image has 1920 pixels horizontally and 1080 pixels vertically. In CCTV systems, the number of pixels directly determines the clarity and detail of the image. The more pixels, the clearer the image and the ability to capture more details, such as clearer facial features, license plate numbers, etc., which is crucial for surveillance and forensics.

For example, a 2MP (megapixels) camera is usually 1920x1080 pixels (about 2 million pixels) in resolution, while an 8MP camera can provide 4K Ultra HD images with much more detail than 2MP.

What is a Lens?

lens is a key component of a camera that captures light and focuses it on the image sensor. The choice of lens directly affects the camera's viewing angle and focal length, which determines the coverage and detail presentation of the surveillance picture.

• Focal Length

  Focal length refers to the distance between the optical center of a lens and the image sensor, usually measured in millimeters (mm). The shorter the focal length, the wider the angle of view (wide angle); The longer the focal length, the narrower the angle of view, but it can magnify distant objects (telephoto).

  • Fixed Lens：The focal length is fixed, providing a fixed angle of view, simple structure, and low cost. Ideal for monitoring fixed areas.
  • Varifocal Lens：The focal length is adjustable, allowing manual or motorized adjustment of the angle of view and magnification, providing greater flexibility.
  • Optical Zoom：Changes the focal length by changing the combination of lenses inside the lens without losing image quality.
  • Digital Zoom：Enlarge a portion of an image, but at the cost of image detail and quality (similar to blurring a picture when zoomed in).

• Angle of View

  The angle of view refers to the horizontal or vertical range that the camera is able to "see". The wide-angle lens (short focal length) provides a wide angle of view and is suitable for monitoring a large area; The telephoto lens (long focal length) provides a narrow angle of view, making it suitable for monitoring distant targets and getting more details.

Choosing the right pixels and lenses is the key to building an efficient CCTV system. Full Secure Sdn Bhd's team of experts will be happy to advise you.