I believe that stating megapixel (HD) camera resolution in TVL is a mistake. For instance, I've seen a few companies who claim a 720P camera delivers 1280TVL of resolution and 1080P cameras deliver 1920TVL of resolution.
There are multiple errors here:
- By definition, TVL is measured over a square section of the video frame where the width equals the total frame height. By design, this spec was intended to ignore aspect ratio so on a 4:3 video frame, the measurement is taken over a 3:3 area and on a 16:9 frame, the measurement is taken over a 9:9 area.
- Despite the obvious problem translating pixels to TVL, which measures the number of vertical black and white lines that can be resolved in that square area before they blur together, the use of TVL for HD doesn't allow for the increased HFOV HD/MP can deliver.