Ubuntu Linux


The libopenalpr-dev package will install the necessary headers and library packages into your system. To install, run:

bash <(curl -s https://deb.openalpr.com/install)

Select install_sdk from the menu.

You must be on Ubuntu version 18.04 or above.


Before running the software you must obtain a license key. If you haven't already done so, please visit the Request a License section to submit your information.

After acquiring a license, paste the license key into the license.conf file to begin using the software. Alternatively, you can set the license as an environment variable named OPENALPR_LICENSE_KEY.

Command Line Utility

The Vehicle Recognition SDK includes a command line utility. Simply type alpr [image file path] to get started with recognizing license plate images.

For example, the following output is created by analyzing this image:

user@linux:~/openalpr$ alpr ./samplecar.png

plate0: top 10 results -- Processing Time = 58.1879ms.
    - LTM378     confidence: 88.9371
    - LTM37B     confidence: 78.1385
    - LTM37      confidence: 77.5444
    - 1TM378     confidence: 76.1448
    - 1TM37B     confidence: 72.9016
    - LTME78     confidence: 72.1147
    - TM37       confidence: 66.7458
    - LTME7B     confidence: 65.3462
    - 1TME7B     confidence: 62.1031
    - 1TM37B     confidence: 61.5089

Detailed Command Line Usage

user@linux:~/openalpr$ alpr --help


   alpr  [-c <country_code>] [--config <config_file>] [-n <topN>] [--seek
         <integer_ms>] [-p <pattern code>] [--clock] [-d] [-j] [--]
         [--version] [-h] <image_file_path>


   -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

   --seek <integer_ms>
     Seek to the specified millisecond in a video file. Default=0

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

     Measure/print the total time to process image and all plates. 

   -d,  --detect_region
     Attempt to detect the region of the plate image.  [Experimental] 

   -j,  --json
     Output recognition results in JSON format.  Default=off

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

     Displays version information and exits.

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

     Image containing license plates

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