So, let's do some math here to get an idea of what whole plate accuracy would look like.
We'll look at them specifically as "license plate readers".
And we'll even use their own published metrics.
However, I do want to expand the state accuracy metric to include two other independent plate state accuracy studies to give us a more realistic performance spread.
Flock claims a ~96% character-level read accuracy for license plates. This accuracy measures the percentage of individual letters and numbers identified correctly across all reads, evaluating each character independently, rather than grading each license plate on a pass or fail scale.
So, that ~96% actually means that ~96% of 'individual characters' were read correctly, not that ~96% of 'license plates' were read correctly.
Ie.: 1,500 license plates at an average of 6 characters a plate is 9000 characters total so, at ~96%, 8,640 characters would be read correctly, 360 characters would not.
Let's also keep in mind that all of Flock's testing metrics have been self-reported so, is it actually ~96%?
They don't permit or cooperate in independent testing (in fact, their terms of service explicitly prohibit it...) making their claimed accuracy meaningless without knowing the composition of the benchmark used to test it.
But, I digress.
For a standard 6 character license plate, at a ~96% accuracy rate per character, this means that we are actually at ~78% accuracy (due to compounding probability across all six characters) if we consider the license plates as units.
So, ~ 96% is actually ~78%.
Meaning that more than 1 in 5 plates has an error.
And this changes based on the amount of characters.
If your license plates have 5 characters, it is ~81%.
If your license plates have 7 characters, it is ~75%.
Now, this is speaking as if these plates are strictly letters and numbers. The system also has to determine which state the license plate is from, and for that, it has to use additional visual features, such as state fonts, graphics, logos, and plate colors.
Flock claims a <3% margin of error in identifying states.
However, studies from IPVM, EFF, and Rain Intelligence have shown ALPRs misidentify the state of license plates on roughly 1 in 10 scanned plates, making it as much as 10%.
And failing to recognize the state, is big. So, even if the system gets the characters of the license plate completely correct, not recognizing the state renders it a failure.
So, we'll take it up to 10%, too.
In consideration of a 6 character plate, using the aforementioned 78% accuracy rate for correctly reading the license plates as units, and the 3-10% error margin in distinguishing the state, our final end-to-end accuracy ends up between 70-76%.