Release Notes


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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