Media Server 25.4
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# Number Plate Recognition

Number plate recognition detects and reads license plates on vehicles.

Configuration Parameter | Description
--- | ---
Boldness | The boldness setting to use for detecting the edges of characters.
ExpectedRotation | The expected amount of rotation (from horizontal, in degrees) for a number plate in the scene.
FreeformRegion | The Region of Interest (ROI) to monitor for number plates, if the ROI is not rectangular.
GPUDeviceID | The device ID of the GPU to use.
Input | The image track to process.
Location | The location(s) for which you are reading number plates.
LocationWithPriorities | The locations for which you are reading number plates, and their relative priorities.
MaxCharHeight | The maximum height of the main characters on the number plate.
MaxInputQueueLength | Can be used to place a limit on latency.
MaxPlatesPerFrame | The maximum number of number plates that you expect to appear in a single image or video frame.
MinCharHeight | The minimum height of the main characters on the number plate.
MinRead | The minimum number of consecutive frames in which a number plate must be visible before a result is generated.
MinValidScore | The average character score required for a number plate to be recognized.
NumParallel | The maximum number of video frames to analyze simultaneously.
OutputAlternativeResults | Specifies whether to return all results, when integration returns more than one result, all for the same plate in the image.
OutputUnformattedResults | Specifies whether to include unformatted results in the output. These are results where the number plate exceeds the confidence score specified by MinValidScore, but does not match one of the expected formats.
Region | The Region of Interest (ROI) to monitor for number plates.
RejectReadsWithInvalidGaps | Specifies whether to reject number plate reads with gaps in the wrong place.
SampleInterval | The interval at which frames are selected to be analyzed.
SegmentDuration | The maximum duration of a record in the `SegmentedResult` or `SegmentedResultWithSource` track.
Sensitivity | The confidence level required to detect a number plate.
Type | The analysis engine to use. Set this parameter to `NumberPlate`.

## Output Tracks

The following table describes the tracks that are generated by this engine. The Output column indicates whether the information contained in the track is included by default in the output created by an output task (when you don't set the `Input` parameter for the output task).

Output track | Description | Output
--- | --- | ---
`Data` | Contains one record, describing the analysis results, per detected number plate, per video frame. | No
`DataWithSource` | The same as the `Data` track, but each record also includes the source frame. | No
`Result` | Contains one record, describing the analysis results, for each recognized number plate. When the same number plate appears in many consecutive frames, Media Server produces a single result. | Yes
`ResultWithSource` | The same as the `Result` track, but each record also includes the best source frame. | No
`SegmentedResult` | (Available only when processing video). The same as the `Result` track, except the duration of each record is limited by the parameter SegmentDuration. If a result exceeds the specified duration, Media Server begins a new record with the same ID. | Yes
`SegmentedResultWithSource` | (Available only when processing video). The same as the `ResultWithSource` track, except the duration of each record is limited by the parameter SegmentDuration. If a result exceeds the specified duration, Media Server begins a new record with the same ID. | No
`Start` | The same as the `Data` track, except it contains only the first record of each event. | No
`End` | The same as the `Data` track, except it contains only the last record of each event. | No

For more information about number plate records, see Number Plate Recognition Results or use the action GetExampleRecord.

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Version 25.4 | Last updated October 2025

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Product: Knowledge Discovery Media Server 25.4

Topic Title: Number Plate Recognition