Forensic Plate Finder

The Forensic Plate Finder processes video or image files (e.g., MPG, AVI, or MP4) to find all of the license plates. The output is a CSV file that lists the license plate information


To use this utility, you must have a commercial license key. Request a free 14-day evaluation key. The license key must be saved in /etc/openalpr/license.conf.


Download and run the OpenALPR Forensic Plate Finder Installer.

After the software is installed, the Forensic Plate Finder will be located in the install directory and as a Windows shortcut on the start menu.


Install the Watchman Agent following the install procedure in the Watchman Agent section.

Run the following command to install the OpenALPR video utility:

curl -L | sudo apt-key add -
echo 'deb bionic main' | sudo tee /etc/apt/sources.list.d/openalpr.list
sudo apt update && sudo apt install -y openalpr-video

After the install is complete, you can execute the alprvideogui and alprvideocli utility directly on the command line.

GUI Usage

Launch the Forensic Plate Finder by clicking the “OpenALPR Forensic Plate Finder” shortcut created by the installer.

OpenALPR Forensic Plate Finder

Once launched, choose Edit->Preferences to select the country, number of processing threads, and the output directory.

Click “Open video…” to select files for processing. The utility can accept:

  • One or more video files
  • One or more JPG image files

Once you’ve selected one or more files to process, click the “Start” button to begin processing. Each file will be processed in order. A spreadsheet for each video file will be placed in the output folder that you specified in the preferences.

Command-Line Usage

Launch the alprvideocli program with a path to a video file. In addition include an output directory; this is where the CSV and SQLite files are saved. The threads option provides more threads to process the video simmultaneously. This should not exceed the number of CPU cores on the machine.


   ./alprvideocli  --output_dir <output_dir> [-c <country_code>] [--config
                 <config_file>] [-n <topN>] [--threads <num_threads>] [-p
                 <pattern code>] [--save_frames] [--debug] [--motion] [--]
                 [--version] [-h] <video_file_path>


   --output_dir <output_dir>
     (required)  Path to the output directory

   -c <country_code>,  --country <country_code>
     Country code to identify (either us for USA or eu for Europe).

   --config <config_file>
     Path to the openalpr.conf file

   -n <topN>,  --topn <topN>
     Max number of possible plate numbers to return.  Default=10

   --threads <num_threads>
     Number of simmultaneous processing threads. Default=1

   -p <pattern code>,  --pattern <pattern code>
     Attempt to match the plate number against a plate pattern (e.g., md
     for Maryland, ca for California)

     Save the image frames for recognized license plates.  Default=off

     Print diagnostic information to the console.  Default=off

     Use motion detection on video file or stream.  Default=on

   --,  --ignore_rest
     Ignores the rest of the labeled arguments following this flag.

     Displays version information and exits.

   -h,  --help
     Displays usage information and exits.

     (required)  Video file containing license plates

   OpenAlpr Forensic Plate Finder


The results are made available in CSV files as well as a SQLite database for querying. The image frames in which license plates were found are also optionally saved to a folder on the disk.

The CSV data is exported in two files. One file shows the individual plate reads, while the other shows the plate groups. For example:

Plate Results:

Plate Results
id group_id country plate_number confidence frame_num video_time_s matches_pattern tracking_hash x1 y1 x2 y2 x3 y3 x4 y4 img_name region region_confidence
1 2 gb CV60UWK 78.4882 70 2.84 1   36 235 176 280 169 314 29 267   gb 0
2 2 gb CV60UWK 75.4025 73 2.96 1   134 180 269 220 260 251 127 209   gb 0
3 2 gb CV60UWK 83.4606 74 3 1   167 159 310 199 300 238 159 196   gb 0
4 2 gb CV60UWK 82.3763 75 3.04 1   198 141 332 180 322 215 189 177   gb 0

Plate groups:

Plate Groups
id country plate_number matches_pattern plate_count frame_start frame_end video_time_start_s video_time_end_s best_plate_id confidence region region_confidence
2 gb CV60UK 0 6 70 77 2.84 3.12 6 82.6058 gb 0
1 gb GP0VZC 0 9 199 211 8 8.48 18 84.4312 gb 0
4 gb GR15RYT 1 2 981 994 39.28 39.8 39 82.4912 gb 0