Release Notes


Release Date: July 1, 2019

  • Significantly faster CPU processing (2x faster on 64-bit Intel processors)
  • Performance improvement on Nvidia GPUs (roughly 40% faster processing)
  • Decreased memory usage on both CPU and Nvidia GPUs
  • Small accuracy improvement across all countries
  • Reduced false positives on road signs and billboards

Web Server:

  • New Dispatch View for real-time alerting (alerts displayed on a map)
  • Text Messaging for alerts
  • Improved user management
  • Additional management REST APIs
  • Usability enhancements for Analytic Reports
  • Improved efficiency

Bug fixes:

  • ONVIF discovery stability issue
  • AlprStream Python binding initialization error when using multiple threads
  • C# Vehicle Classifier binding bug


Release Date: March 26, 2019

  • Windows GPU support for both Agent and SDK
  • Added Support for Singapore and Malaysia license plates
  • Extended Support for all countries in the Gulf Cooperation Council. All emirates in UAE are now differentiated
  • Extended support for Mercosur format in Brazil
  • Improved accuracy for Japanese plates (smaller provinces, green plates, and low-numbered plates)
  • GPU support for multiple cards in one server
  • Encoding JPEG on GPU when available (reduces CPU load)
  • Small (~10KB) JPEG crop for the plate and vehicle are sent with plate group JSON result by default
  • Supporting custom branding/white-labeling for OpenALPR configuration utility
  • More efficient H264 decoding

Bug fixes:

  • Fixed performance issue related to retrieving recorded video in the agent
  • Added upload option for second beanstalkd tube
  • Writing heartbeat data to second tube
  • Added disk size stats to heartbeat data
  • Added command line option to toggle GPU on alpr command line program
  • Fixed rare race condition crash in stream processing
  • Faster GPU initialization

API Changes:

  • Alpr: Can initialize Alpr instance as GPU or CPU using the constructor (without modifying the configuration file)
  • Alpr: Added getters for GPU settings
  • Alpr: Deprecated prewarp function. It no longer contributes to accuracy
  • Alpr: Added GPU batching functions to C API (can be used on Windows)
  • AlprStream: Added vehicle_jpeg crop value to AlprGroupResult
  • AlprStream: Added Python binding

Archived Windows Installers

Archived Linux Repositories


Release Date: October 5, 2018

  • Accuracy improvement across all countries
  • H264 video recording in the agent (simplistic NVR capability)
  • Russian license plate recognition with province support
  • Improved plate tracking for stop-and-go traffic
  • Recognition for additional countries in the middle-east (Qatar, Egypt, Bahrain, Iraq, Jordan, Kuwait, Oman)
  • Extended European support to include two-line license plates
  • Extended Brazil and Argentina support to include two-line license plates
  • Direction of Travel tagging in the Web UI
  • Analytics reports in the Web UI
  • Added Nvidia support to Ubuntu 18.04 using CUDA 10.0

Bug fixes:

  • Video streams better maintain input framerate under high CPU load
  • Improved selection of best plate group images. Images with a plate and a vehicle outside of the image frame are less likely.
  • Fixed race condition on initialization (thread safety issue) in ALPR API Python binding
  • Fixed .NET binding issue in the “recognize” function when using an encoded image in-memory.
  • Fixed .NET UTF-8 decoding issue (better support for plates with international characters)
  • Fixed video buffering issue in the Agent that, in some cases, caused significant video buffering and delays
  • Fixed issue causing direction of travel value to be set to 0 in certain some cases
  • Fixed bug in the agent where video files (used as cameras on automatic loop) with spaces in the filepath would not load
  • Faster default timer for sending plate groups
  • Fixed issue where results could back up on the agent when processing cameras with extremely busy roads (e.g., highways)
  • Agent buffers and retries POSTs when an HTTP 500 is received

API Changes:

  • AlprStream: Added JSON deserialize function
  • AlprStream: Added option to serialize plate crop image in JSON
  • AlprStream: Added set_location function for mobile applications (GPS lat/lng coordinates will be sent in JSON payload)
  • Alpr: Added JSON deserialize function

Archived Windows Installers

Archived Linux Repositories


Release Date: March 5, 2018

  • Massive Nvidia GPU performance improvement 100%+ faster throughput (fps) on desktop GPU, even larger improvement on Jetson
  • Performance improvement for CPU-only processing (~10-15%)
  • Significantly improved efficiency and some usability improvements for live video preview
  • Small accuracy improvement for all supported countries
  • Small accuracy improvement for recognition on GPU
  • Vehicle: Improved make/color/body type detection.
  • Vehicle: Added vehicle orientation and year.
  • Vehicle: Added make/models for many countries (previously this was exclusively USA cars)
  • New countries: Japan and Indonesia
  • Added province detection for Australia, Japan, UAE, South Africa, Indonesia
  • Better accuracy in Great Britain for 1 and 2-line license plates
  • Web Server: Professional PDF report export for plate reads and alerts
  • Web Server: Search Auditing
  • Web Server: Search by State/Province
  • Web Server: Support both whitelists and blacklists for alerting
  • Web Server: Automatically add camera name/agent hostname to new agents

Bug Fixes:

  • Fixed rare race condition when video reconnects after losing connection
  • Fixed small memory leak when parsing metadata for certain video formats

API Changes:

  • AlprStream: Added queue_empty to API response object
  • Vehicle: Added “country” parameter to vehicle classifier
  • Vehicle: Added orientation/year to output
  • State Recognition: Prefixing USA states with “us-” to be consistent with other countries

Archived Windows Installers

Archived Linux Repositories


Release Date: December 3, 2017


  • New ALPR configuration GUI for Windows/Linux agents.
  • Added South Korea and Great Britain training data
  • Better handling for plates extending beyond the edge of the image
  • Improved support for automatically detecting RTSP/MJPEG stream URL decoder types
  • Improved (more accurate/smoother) statistics generated from AlprStream
  • Removed unused GStreamer plugin DLLs from package
  • Agent now stores and uploads “plate groups” by default - 3-10x longer image storage retention
Bug Fixes:
  • Added missing ROIs from ALPR results
  • Fixed relatively small memory leak (~200KB / day of continuous usage) in AlprStream
API Changes
  • ALPR API: Added perspective corrected plate crop (JPEG bytes) to ALPR results object
  • ALPR API: Added license key parameter to constructor
  • AlprStream: Added “motion_stickiness” parameter to adjust how long motion detection lingers over areas
  • AlprStream: Added configurable GStreamer pipeline for more comprehensive input stream support
  • AlprStream: Added “candidates” to each plate group object which contains top N other possible plate numbers
  • AlprStream: Added “user_data” value that contains arbitrary user_data sent along with the group/plate results
  • AlprStream: Added image width/height to AlprGroup results


Release Date: October 11, 2017

Major new features:
  • Nvidia GPU Support for Linux enables high-speed ALPR acceleration.
  • New country support: Argentina, Brazil, China, India, New Zealand, Saudi Arabia, South Africa, Thailand, and the UAE
  • Accuracy improvement for North America, Europe, and Australia
  • Accuracy improvement for US state recognition
  • 30-50% faster recognition performance on Windows (Windows and Linux performance are now roughly the same)
  • New AlprStream API officially released -
Minor new features
  • Parked car detection (when a plate is detected subsequent times and has not moved, it is flagged as parked)
  • Direction of travel indication (the direction that the plate has traveled is available with the results)
  • Open Sourced the OpenALPR rolling image data storage module (RollingDB) under LGPL license:
  • Reduced overall memory usage
  • Added Australian province detection
  • Small accuracy improvement for vehicle classifier
  • Added option to skip state/province recognition - reduces computation cost if state recognition is not needed
  • Added option to skip plate recognition (library returns candidate plate locations without character identification)
  • Added an agent option to upload only plate group data
  • Significantly better accuracy for US commercial tractor-trailer license plates
  • Added plate number overlay to the debug visualization
API Changes:
  • Deprecated setDetectRegion and moved the option to openalpr.conf
  • Added recognize_batch functions that accept and process multiple images simultaneously for optimal GPU processing efficiency
Bug fixes:
  • Fixed .NET binding in SDK to point to proper shared library
  • Increased default number of upload threads in the agent to better support high-latency connections
  • Fixed various user-interface bugs for Forensic Plate Finder
  • Fixed grouping bug that would, in certain cases, produce duplicate results
  • Better handling of disk storage when the agent PC is low on disk space
  • Including more detailed logging for agent video connections
  • Fixed agent bug that allowed incoming video frames to buffer without bound under certain configurations
  • Numerous minor bug fixes


Release Date: July 7, 2017

Major Features:
  • Upgraded recognition engine. Significant accuracy improvement for US, Europe, and Australia. Recognition frame rate is slightly improved.
  • Higher accuracy US state of issuance recognition. Also includes Canada and Mexico
  • Refactored Stream processing into a library. The “alprstream” API is released as a beta – the API is subject to change before the official release. The alprstream API allows application integrators to embed OpenALPR video processing
  • New product: Video file processing utility (OpenALPR Forensic Plate Finder)
Minor Features:
  • Higher accuracy vehicle recognition
  • More even frame recognition when video rate exceeds processing capacity
  • Faster ALPR group results
  • Remote opt-in crash reporting on Linux
  • Option to store a single plate image for a group
  • Pruned unnecessary gstreamer libraries from Windows installer package
  • Applying detector mask to motion detection (improves processing efficiency)
  • Config option to only upload plate groups
  • Improved websockets responsiveness (supports parallel requests)
Bug fixes:
  • Fixed race condition that caused image write thread failure on startup
  • Fixed thread safety issue with plate grouper
  • Fixed invalid JSON output (duplicate img_width/img_height)


Release Date: August 29, 2016

Major Features:
  • Accuracy/performance improvements
  • Vehicle make/model/color recognition (previously available as a separate API) integrated with ALPR Agent
  • Refactored Windows Agent/SDK code to remove all Linux emulation. Windows binaries run fully natively.
Bug fixes:
  • Resolve a small memory leak

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