Resolution has problems.
IP cameras equate resolution with pixels, ignoring that pixels are simply mechanical components of a camera, not the full performance of said camera. Indeed, it has gotten so bad, we have recommended that we Ban Resolution.
Classic Resolution Metric
With analog cameras, resolution was always defined by line counts (aka TV line counts or horizontal TV lines), which measured the actual details that the full camera could deliver.
In fairness, line counts were far from perfect. They only considered ideal lighting conditions and ignored digital recording. Plus, manufacturers went crazy with them, leading to analog insanity of spiraling, but pointless, TV line counts of 600 to 700 to 800 to 900 to 1000.
However, at least line counts attempted to measure real world performance, not just count parts on a chip (i.e., number of pixels = resolution).
The IP TV Line Test
IPVM is bringing back the TV line test and introducing it to IP / MP cameras.
The setup is an ISO 12233 chart with a camera positioned to capture the area of the chart. The image below shows an IP camera being tested:
We then measured the number of TV lines different cameras delivered in various conditions. Here is an example of two test charts:
Notice that in chart 1, the number of TV lines visible is ~450-500 while chart 2 on the right is much higher, 1,000-1,200.
This test answers the following key questions:
- How does pixel count relate to line count?
- How much are line counts reduced in lower light?
- How much does compression impact line count?
- What other factors impact line count?