License plate recognition (LPR)

What LPR does

You can use plate events for alerts and to find video fast.

Must-knows

• Smart AI detection must be on, with Car picked, for plate reading to work.
• The plate must be in view for more than 1 second. Faster cars won't be read.
• Only single-line plates can be read right now.
• The plate must be at least 100 pixels wide in the picture. 150 or more is better.

Pick the right camera

Most modern cameras can work. The best ones let you set shutter speed, frame rate and bitrate yourself. Any resolution is fine as long as the plate is wide enough. A narrow lens on a basic camera can be enough. A wide fisheye camera far away is not.

Place it well

• Put the camera at a gate, entrance or driveway where cars must pass.
• Mount it at road level, or just a bit above car height.
• Cars should drive toward or away from the camera, not across it.
• If your area doesn't require front plates, aim at the back of the cars.

Get the light right

• The plate needs even, steady, soft light.
• Avoid direct sun on plates, garages with big windows, spots with lights that switch on and off, and bright spotlights.
• If there's bright light behind cars, raise the camera's brightness above auto so the plate is readable.
• Features like WDR and backlight help can blur plates. A sharp plate with some dark or bright spots beats an evenly lit blurry one.

Camera settings

• Use a low-motion-blur mode if your camera has one.
• Shutter: no slower than 1/100 of a second. 1/150 or faster is better. A darker sharp picture is better than a bright blurry one.
• Frame rate: 8 to 15 for slow cars. Raise it for fast roads. The plate should show in at least 5 pictures.
• Get good contrast in the picture.
• Too much sharpness adds noise and false motion. Fix it with better light.
• Blurry "tails" behind cars? Raise the bitrate and shorten the keyframe interval.