Analog vs. Digital Resolution – TV Lines (TVL) vs. Pixels
One of the most confusing and difficult topics in the CCTV world is resolution. Most of us have digital cameras or video camcorders and have heard the term megapixel used as the most common comparison in resolution between various makes and models. We are also aware that a larger number means better picture quality, but many people do not know why. In the CCTV security camera world, though, most cameras are still analog and their resolution is measured differently from what we are used to.
When measuring analog resolution, a TV line does not have a defined number of individual pixels. Instead, the term “TV lines” refers to the number of discernable horizontal or vertical lines on the screen. Analog security cameras are measured in Analog TV Lines, and most of them have between 420 and 580. The higher number of TV Lines, the more information captured. These types of cameras connect to a security DVR or CCTV VCR via coaxial video cable.
A pixel is the smallest element of a digital image. We have all zoomed too far into a picture from a website and seen the image go from clear to a bunch of colored squares – each one of those squares is an individual pixel. A megapixel (MP) is 1 million pixels, and is a specific measurement for digital resolution that encompasses the area of the output video.
Example: If a camera outputs a signal that is 1280×1024 pixels, it is shooting at a megapixel resolution of 1280 x 1024 = 1,310,720 pixels = 1.3 Megapixels (MP).
The most common type of digital security cameras are IP Cameras. These, like your digital camera at home, use strictly digital resolution. They utilize a network connection to either act as a standalone device or connect to a network-based DVR (Digital Video Recorder) or NVR (Network Video Recorder). IP Cameras have fixed resolutions and are now approaching, and in several cases exceeding, 1 megapixel in resolution, on average. Many of these cameras also support POE (Power Over Ethernet), which allows them to be powered by the Ethernet cable used for network connectivity, and PTZ (Pan Tilt Zoom), allowing for remote control of the pan, tilt and zoom features, if applicable.
I hope this helped everyone distinguish the differences between Analog (TV Line) and Digital (Pixel) Resolution. We would love to know what you think of our articles, and if you have any further questions, don’t hesitate to leave a comment!