Definition and TVLine

Definition refers to the clarity of the detailed pattern and its borders video images.

Definition, generally from the the point of view of VCR, compare the image quality by the clarity of the image replayed, so the term commonly used the world definition. While The camcorder generally used resolution to measure it ability: "decompose the details of scene photographed". Unit is the "TV lines (TVLine, TVL)" also known as line. Means that , equivalent to erect each line of scan lines the horizontal direction from the point of view, and then multiplied by 4 / 3 (Aspect Ratio), Constitute the total number of lines in horizontal direction, saying the horizontal decomposition force. It changes with the number of CCD Pixels, and the video bandwidth, the more pixels and the wider bandwidth is, the higher the decomposition ability is. The 625-line of PAL system is the the nominal vertical decomposition ability, except the the 50 lines in reverse process, the actual effective vertical decomposition ability is 575 lines. The level of decomposition ability up to 575x4/3 = 766 lines. But one of the major factors restricting the lines number is bandwidth. Empirical data shows that use 80 lines / MHz to calculated to reproduce the TV lines (line number) is available. Such as can use 6MHz bandwidth to transmit image quality have 480 line decomposition ability. Low-end home use video recorder, such as VHS, can have up to 240 lines of resolution. Digital camera record data in digital signal format, resolution up to 500 lines or more. (Normal TV resolution is about 280 TVLines, VCD's resolution is 230 TVLines).


Relate links:
520TVL IR CCD Camera
380TVL 1/3 CMOS Camera
480TVL IR Weatherproof Dome Camera