anpr

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Erlang example

https://github.com/bobhyun/TS-ANPR/tree/main/examples/Erlang/anpr

1. Copying the Engine Files

[Note] In this example, the engine file is extracted to the examples/bin/ directory to share it with other examples. However, for actual deployment, the engine file is typically copied to the directory where the application's executable file is located.

• For Windows x86 64-bit Extract the engine file to the examples/bin/windows-x86_64 directory

  7z x tsanpr*-windows-x86_64.7z

• For Windows x86 32-bit Extract the engine file to the examples/bin/windows-x86 directory

  7z x tsanpr*-windows-x86.7z

• For Linux x86 64-bit Extract the engine file to the examples/bin/linux-x86_64 directory

  tar xvf tsanpr-linux-x86_64.tar.xz

• For Linux arm 64-bit Extract the engine file to the examples/bin/linux-aarch64 directory

  tar xvf tsanpr-linux-aarch64.tar.xz

• Directory structure

  examples
  ├── bin
  │   ├─── windows-x86_64        # engine directory for Windows (x86_64)
  │   │   ├── tsanpr.dll
  │   │   ├── tsanpr-2505M.eon
  │   │   └── tshelper.exe
  │   ├─── windows-x86           # engine directory for Windows (x86)
  │   │   ├── tsanpr.dll
  │   │   ├── tsanpr-2505M.eon
  │   │   └── tshelper.exe
  │   ├── linux-x86_64           # engine directory for Linux (x86_64)
  │   │   ├── libtsanpr.so
  │   │   ├── tsanpr-2505M.eon
  │   │   └── tshelper
  │   └── linux-aarch64          # engine directory for Linux (arm64)
  │       ├── libtsanpr.so
  │       ├── tsanpr-2505M.eon
  │       └── tshelper
  ├── img                        # image directory
  └── Erlang
      └── anpr                   # project directory
         ├── c_src               # C NIF source files
         │   └── tsanpr_nif.c
         ├── src                 # Erlang source files
         │   ├── anpr_app.erl    # Application behavior
         │   ├── anpr_sup.erl    # Supervisor behavior
         │   ├── anpr.erl        # Main module
         │   ├── tsanpr.erl      # NIF wrapper module
         │   └── anpr.app.src    # Application resource file
         ├── priv                # Compiled NIF libraries
         │   └── tsanpr_nif.dll/.so
         ├── rebar.config        # rebar3 configuration
         └── _build              # rebar3 build output (generated)
            └── default
               └── lib
                  └── anpr
                     ├── ebin    # Compiled .beam files
                     └── priv    # NIF libraries

2. Prerequisites

1. Install Erlang/OTP (version 24 or later recommended)

   Windows:

   # Download from https://www.erlang.org/downloads
   # Or using Chocolatey
   choco install erlang

   Linux:

   # Ubuntu/Debian
   sudo apt-get update
   sudo apt-get install -y erlang
   
   # Oracle Linux / RHEL / CentOS (8/9+)
   sudo dnf install -y erlang || sudo yum install -y erlang
   # Tip: If erlang is not found, enable EPEL or use Erlang Solutions repo:
   # https://www.erlang.org/downloads
   
   # Or using kerl (recommended)
   curl -O https://raw.githubusercontent.com/kerl/kerl/master/kerl
   chmod a+x kerl
   ./kerl build 24.3 24.3
   ./kerl install 24.3 ~/erlang/24.3
   # Activate this Erlang in current shell
   . ~/erlang/24.3/activate
   # (To deactivate later) run: deactivate

2. Install rebar3

   Windows:

   Download the latest rebar3 escript from GitHub:

   # Download latest rebar3 (compatible with Erlang/OTP 28+)
   Invoke-WebRequest -Uri "https://github.com/erlang/rebar3/releases/latest/download/rebar3" -OutFile "rebar3"
   
   # Place rebar3 in your project directory or move to a directory in your PATH

   Note: On Windows, rebar3 must be run using escript rebar3 <command> (not just rebar3 <command>).

   Linux:

   # Ubuntu/Debian
   sudo apt-get install rebar3
   
   # Or download latest from GitHub
   wget https://github.com/erlang/rebar3/releases/latest/download/rebar3
   chmod +x rebar3
   sudo mv rebar3 /usr/local/bin/

3. Install C compiler (required for building NIF)

   Windows:

   • Install Visual Studio with C++ development tools, or
   • Install MinGW-w64: choco install mingw

   Linux:

   # Ubuntu/Debian
   sudo apt-get install build-essential
   
   # Fedora/CentOS
   sudo yum groupinstall "Development Tools"

4. Verify installation

   erl -version
   rebar3 version
   gcc --version  # or cl.exe on Windows with Visual Studio

3. Build and Run

1. Navigate to the Erlang example directory

   cd examples/Erlang/anpr

2. Build the NIF (Native Implemented Function) library

   Windows:

   Open "x64 Native Tools Command Prompt for VS" (or run vcvars64.bat), then:

   build_nif.bat

   This will:

   • Automatically detect your Erlang installation
   • Compile c_src/tsanpr_nif.c using MSVC
   • Create priv/tsanpr_nif.dll

   Linux:

   make priv/tsanpr_nif.so

   This will:

   • Compile c_src/tsanpr_nif.c using gcc
   • Create priv/tsanpr_nif.so with proper linking to libdl

3. Build the Erlang application

   Windows (use escript command):

   escript rebar3 compile

   Linux:

   rebar3 compile

   This will:

   • Compile Erlang modules (anpr.erl, tsanpr.erl) to _build/default/lib/anpr/ebin/
   • Copy the NIF library from priv/ to _build/default/lib/anpr/priv/

4. Run the application

   # Non-interactive mode
   erl -pa _build/default/lib/anpr/ebin -noshell -eval "anpr:main()" -s init stop
   
   # Interactive mode
   erl -pa _build/default/lib/anpr/ebin
   1> anpr:main().

4. Notes

• This Erlang implementation provides the same functionality as other language examples
• Uses Erlang's NIFs (Native Implemented Functions) to interface with the native TSANPR library
• Erlang's fault-tolerant design and lightweight processes make it excellent for concurrent systems
• Cross-platform support for Windows and Linux
• Built using rebar3, the standard Erlang build tool
• The project follows rebar3-standardized structure for better maintainability
• Note: This is a simplified NIF implementation for demonstration purposes

5. Features

• File-based recognition: Process image files directly
• Encoded image processing: Handle encoded image data (JPEG, PNG, etc.)
• Pixel buffer processing: Process raw pixel data (simplified implementation)
• Multiple output formats: Support for text, JSON, YAML, XML, and CSV output
• Multiple recognition modes: Single plate, multiple plates, vehicle detection, etc.
• Region of Interest (RoI): Process specific areas within images
• Multi-country support: Support for different license plate formats (KR, JP, VN, etc.)

6. API Reference

tsanpr Module

The tsanpr module provides the following functions:

Initialization:

• tsanpr:new(LibraryPath): Initialize with native library path

Core Functions:

• tsanpr:anpr_initialize(TSANPR, Mode): Initialize the ANPR engine
• tsanpr:anpr_read_file(TSANPR, ImgFileName, OutputFormat, Options): Process image file
• tsanpr:anpr_read_pixels(TSANPR, Pixels, Width, Height, Stride, PixelFormat, OutputFormat, Options): Process pixel data

Recognition Options

• "": Single license plate recognition (default)
• "vm": Recognize multiple license plates attached to vehicles
• "vmb": Recognize multiple license plates attached to vehicles (including motorcycles)
• "vms": Recognize multiple license plates attached to vehicles with surround detection
• "dms": Recognize multiple surrounding objects (vehicles)
• "dmsr": Recognize multiple surrounding objects (vehicles) and license plates
• "dmsri<coordinates>": Recognize within Region of Interest

Output Formats

• "text": Plain text output
• "json": JSON format output
• "yaml": YAML format output
• "xml": XML format output
• "csv": CSV format output

7. Troubleshooting

Library Loading Issues:

• Ensure the TSANPR library path is correct
• Check that all system dependencies are installed
• Verify library permissions are correct

NIF Issues:

• This example uses a simplified NIF approach for demonstration
• For production use, you would need to implement proper C NIFs
• Ensure Erlang development headers are installed

Compilation Issues:

• Ensure Erlang compiler is properly installed
• Use erlc to compile modules before running
• Check for syntax errors in .erl files

Platform-Specific Issues:

• Windows: Ensure Visual C++ Redistributable is installed
• Linux: Install required system libraries and ensure library permissions are correct