What’s a better resolution for a low light video surveillance camera – 1080p or 720p and why?
A: There’s a case to argue that the best CCTV resolution is greater than 1080p or 720p – it might be 5MP – the trick will be selecting a camera with a sensor size and a cleverly designed camera engine capable of making the most of the resolution. Another factor is going to be integrated light sources – these do add capability, though not everyone favours their use.
When it comes to deciding between 720p or 1080p in low light applications, both have their place, depending on what you need. There are going to be applications with narrow angles of view and shallow depths of field that will be well served by 720p resolutions, especially if bitrate is a secondary consideration. Having said that, the latest compression technologies and protocols do make questions of slight variables like 720p vs 1080p much less of an issue.
Low light performance differences, which were a big deal in early generations of IP cameras, are no longer such a concern. There are applications where you might select low resolutions in order to facilitate larger pixel sizes, but cameras designed this way are likely to be specialised.
Would a 1/3-inch sensor with 720p resolution deliver better low light performance than a 1080p sensor, all other things being equal, thanks to larger photo-sites? Yes, it would. This is going to play into other characteristics of your image stream, including reduced amplification, less motion blur and less in the way of digital work required during the process of building the image stream. All these elements will increase sharpness and enhance ID of faces and numberplates.
Something else to consider is that optical zoom beats digital zoom hands down. Given this, slightly more resolution will be an improvement if you intend to use some digital zoom to scrape a little more information from a scene. At the same time, using a longer lens will aggregate pixels – carefully assessing the angle of view required will deliver the resolution you need where you need it, as well as delivering the enhanced low light performance of larger photo-sites.
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