Can LPR Accurately Identify 100% of the Cars Scanned?

January, 2021

John Van Horn

This is one of those situations where you have to know the answers before you ask the questions. Most LPR companies would tell you that they read license plates in the high 90 percent range. Fair enough. However, that’s of license plates that can be read.

I understand there are
more than 50 different designs in California alone.

What about plates behind a bike rack, or trailer hitch, or covered with mud or snow or ice? What about cars with no plates, or dealer plates in the rear window? What about plates from a foreign country with strange characters or fonts?

I remember a few years ago talking to an LPR company rep in the UK. I asked him what the percentage read rate was. He asked me where the reading was taking place. I said “In the UK.” He said “Better than 99 percent, a requirement by the government to provide LPR technology to the police and enforcement agencies.” I then said, “In the U.S.” When he stopped laughing, he said, “Maybe in the mid 80 percents, on a good day.”

Seems that in the UK, all license plates are the same – that is white on black, and the same font. In the U.S., every state is different, plus in most states, there are different designs, pictures, and PR slogans. I understand there are more than 50 different designs in California alone. The computer must be trained to differentiate between all these and do it accurately.

Technology has moved on since my conversation in the UK. However, even if the camera/computer combination is capable of reading and decoding 100 percent of plates it can see, what about those obscured in the ways listed in the paragraph above?

If I am scanning cars on the freeway, or those parked on a city street, and miss a few, I could say “so what?” I’m still probably getting more accuracy that if I was relying on a PEO entering data on their hand held. But what if I’m relying on LPR to allow vehicles to enter and exit a garage? If I miss 10 percent and don’t have any other way to get them in or out, I have a real problem in the lanes.

Granted, the read rate may be higher in garages because the cars are stopped, the cameras aligned perfectly, and lighting is ‘just right.’ But still, some will be missed.

The point is that when you ask about read rates, be sure you ask the right questions. The answers may all be true, but not all are helpful.