node-openalpr

This package binds OpenALPR with Node.js

Version: 1.1.0 - Released January 4th, 2016

Changelog:

1.1.1   - Fix for building on OSX
1.1.0   - Updated OpenALPR to version 2.2, should fix Linux and OSX builds
1.0.9   - Updated OpenALPR build and US region data
1.0.7   - Added the capability to specify regions
1.0.6   - Slowed down the event loop to 30 times per second
1.0.1:5 - Documentation changes
1.0.0   - Initial release

Installation and Example

Use npm to get the node-openalpr package. We'll attempt to use node-pre-gyp to compile from source, but if that's not possible we'll fallback to precompiled binaries.

Linux

0. Install OpenALPR
1. Run npm install node-openalpr

Windows

0. Run npm install node-openalpr

OS X

0. Install OpenALPR (this installation may lead to some error in the binary compilation, manual compilation may be requested. For the compilation issue see this suggestion: https://github.com/openalpr/openalpr/issues/658#issuecomment-482913493.)
   • OpenALPR
   • using Homebrew(openalpr v2.2.0)
1. Run npm install node-openalpr

Example

var openalpr = require ("node-openalpr");

function identify (id, path) {
    console.log (openalpr.IdentifyLicense (path, function (error, output) {
        var results = output.results;
        console.log (id +" "+ output.processing_time_ms +" "+ ((results.length > 0) ? results[0].plate : "No results"));

        if (id == 349) {
            console.log (openalpr.Stop ());
        }
    }));
}

openalpr.Start ();
openalpr.GetVersion ();

for (var i = 0; i < 350; i++) {
    identify (i, "lp.jpg");
}

Methods

This is a breakdown of all of the methods available for node-openalpr. Start needs to be called before any other method.

• openalpr.Start ([config[, runtime[, count[, start_queue]]]]) - Initializes OpenALPR with default settings
  • config - Path to configuration file. On Windows defaults to the config file in node-openalpr directory, on Linux defaults to openalpr installation
  • runtime - Path to runtime data. On Windows defaults to "openalpr_runtime" folder in node-openalpr directory, on Linux defaults to openalpr installation
  • count - Number of concurrent OpenALPR processes to run - defaults to CPU core count
  • start_queue - Auto start queue monitoring thread - defaults to true
• openalpr.Stop () - Stops the OpenALPR processes and clears out any queued images
• openalpr.StartQueue () - Starts the OpenALPR queue monitoring thread (normally started automatically after calling Start ())
• openalpr.StopQueue () - Stops the OpenALPR queue monitoring thread
• openalpr.queueLoop () - Method used in checking queue - can be called manually if start_queue is false for finer control
• openalpr.IdentifyLicense (path, options/callback[, callback]) - Begins the process of identifying a license from the given image, returns "working" or "queued" status result
  • path - Path to image - if image does not exist an exception will be thrown
  • callback/options - Additional options for the image or a callback
  • options.state (string) - State ("oh") license plates are in for additional validation
  • options.prewarp (string) - Prewarp configuration information
  • options.detectRegion (boolean) - Use detect region functionality of OpenALPR? (slower)
  • options.regions (array) - Specify the regions of the image to work on (format: [{ x: 0, y: 0, width: 0, height: 0 }, ...]
  • callback - Callback with results: function (errors, output)
• openalpr.GetVersion () - Get the version of OpenALPR currently being run against

How to Compile

0. Download and install io.js v3.0.0+
1. Download and install git
2. Download and install cmake

Windows

0. Download and install Visual Studio 2013/2015
1. Run PowerShell ISE as an administrator and execute: Set-ExecutionPolicy RemoteSigned
2. Run openalpr-install.ps1
3. Take output from openalpr/windows/build/dist and put into "lib" and "release/win32" folder in node-openalpr
4. Run npm install

Linux

0. Run openalpr-install.sh
1. Run npm install

Features, Bugs and Collaborating

All of the code is provided as-is. We will not provide on-going support for any bugs that may be found. Please submit bug and features requests - we will review them but we do not garunteed that they will be addressed. Pull requests are welcome and we'll review them as quickly as we can.