Surveillance Image Quality
Any robust security system includes high-quality surveillance cameras as an integral part of event tracking and monitoring. The primary function of your security cameras is to let you see events on your property, both recorded and in real-time. To see these events, you need good image quality from your cameras – but sometimes “high quality” isn’t high enough.
Your cameras record in a certain resolution, usually measured in megapixels (MP), but can be converted to their pixel dimensions. Wireless cameras are generally limited to 1.3MP, or 1280 x 1024 pixels, sometimes shortened to 1024p. This might sound high, but the actual image quality is not good enough for digital zoom and enhancement. Even HD feeds – 1920 x 1080p – can’t generally be enhanced enough to make out details like faces or license plates. 2048 x 1536p resolution, or 3MP, is about the minimum needed to reliably make out specifics with digital zoom. The best resolution for most security cameras is 4K resolution – 3840 x 2160p or about 8MP.
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While higher resolution is more expensive, you get a lot more out of your security cameras when they can actually make out the details of an image. But there’s also a point at which you’re paying for resolution you don’t need – you probably don’t need 14MP resolution to make out license plates and faces.
So why do you need higher resolution for digital zoom? Because digital zoom simply magnifies a portion of the image or video, you’re actually limiting your resolution to the size of that section. The higher your base resolution, the further you can zoom in before the image quality becomes a pixelated mess. The same cropped section of the image contains more pixels, enabling you to make out more details.
While digital zoom reduces your effective resolution, cameras with optical zoom don’t lose any quality when they zoom in. Instead of altering the resolution window, optical zoom changes the focal length of the camera’s lenses to tighten the field of view. The only downside is that optical zoom can only be done in real-time – once the footage is recorded, you obviously can’t use the camera’s lens to zoom in.
Angle and Field of View
One of the challenges of surveillance zoom cameras can’t solve is filling blind spots – at least, not unless you install another one. To ensure full coverage with fewer cameras, you need something with a wider field of view.
Wide-angle cameras equipped with specially designed lenses to provide an overview of an area rather than a tight detail perspective. This large field of view comes at the cost of distortion, though. Straight lines appear curved through a wide-angle lens, with the edges of the image more distorted than the center.
Virtually any camera can come with a wide-angle lens, and some optical zoom cameras can zoom out far enough to essentially become wide-angle lenses. Most wide-angle cameras are security domes, so potential troublemakers can’t tell which way they’re really pointing.
The widest angles are provided by fisheye lenses – some of them even offer a 360-degree picture. The catch is the massive distortion necessary to put the entirety of a room onto a comparatively small screen. This can be solved with a dewarping program, either on the camera itself or in your video management software. The dewarping can do some strange things to the image resolution, but fisheye cameras aren’t designed to pull details. They’re meant to provide a general overview for a breadth of surveillance, not depth.
Panoramic and Multi-lens cameras
Other cameras capture a wide field of view by simply adding more lenses facing in different directions. These systems stitch together multiple feeds to create a panoramic view instead of dewarping the image. They have the advantage of still providing most of the picture if one lens is damaged. They can be more expensive than traditional domes, though.
Choosing Your Cameras
Regardless whether you choose high-zoom, wide-angle lens, panoramic cameras, or a mix of all three, you need a high enough resolution to ensure your surveillance system meets your needs. The best security camera networks are planned out beforehand by professionals, typically through a consultation that details blind spots and ways to maximize coverage.