5 - Understanding Resolution & Frame Rates
Resolution
A camera's resolution is a function of the number of pixels the video chip provides. Pixel (derived from "picture element") is the basic unit of programmable color on a computer display or digital image. Pixels are arranged in formats such as 2 megapixel, which is 1600 horizontal pixels stacked with 1200 vertical pixels. A 4K image (8 megapixel) is comprised of 3840 x 2160 pixels. "4K" refers to horizontal resolutions of around 4,000 pixels.
NOW FORGET ALL OF THAT!
None of it matters, lets keep it simple, the chart below is all you need to know.
For true 4K video to be viewed, there are four components that must be 4K capable. The camera must be able to record and transmit 4K video, the recording device must have 4K capability, an HDMI cable must be used to connect the recorder to the monitor, and the monitor must be a 4K monitor. If any of these devices are not 4k capable, then the video resolution will be limited to the component with the lowest resolution.
Most PC monitors are 1080p (2mp). The image looks great but does not have the crisp quality a 4K monitor provides. If you have a 4K system and a 1080p monitor, you will still get the digital zoom benefits of a 4K system, but the viewing clarity will be affected.
One of the most common mistakes a novice makes is thinking that if they use a 4K camera then they'll see all the detail they'll ever need. The reality is that the camera's lens is just as important as the video chip. You must match the resolution to the lens which depends on the application. The video below is a good example. It was made with a 3K camera equipped with a long-range zoom lens. The reason we can easily read the license plates is because the zoom lens was used to target a specific area about 40 feet wide where the vehicles plates consistently pass. Then after recording we digitally zoom into the 3K image to capture the plate. This would not be possible with a 4K camera that did not have a zoom lens that could reach the target distance.
4K Video Samples
3K Video Samples
Frame Rates
Frame rate is how many still frame images are generated every second. Live video contains 30 frames per second. Motion pictures are filmed at 24 frames per second. We offer cameras that produce 20 and 30 frames per second. The benefit of using 20 fps cameras is that you can store 30% more video on the hard drive, simply because there are less frames to store.
Video recorders allow you to set the frames per second for each individual camera. If you reduce the fps, all future files will drop in size, allowing more video to be stored. However, the video will become choppier as the frame rate is reduced. If you are trying to capture plates, target a location where the vehicles are moving slowly, such as speed bumps, entry points, bottle necks, and turns, the best recommendation is to record at the maximum frame rate (20fps or 30fps). This will help to counter the motion blur caused by the vehicle's movement. If you reduce the recorded fps, it will not affect live viewing. The live viewing feed will be presented at the camera's maximum frame rate.
Best advice: We high recommend you stay away from 15fps cameras even if they are 4K resolution. There are many on the market that look like a good buy but they have some huge performance problems. The images are clear while objects are stationary but the instant an object moves (vehicles or individuals), the video blurs loosing all detail and producing useless video.