[Openalpr] 如何產生測試用的車牌影像

以下介紹幾種方式，可以取得測試用的車牌影像

[Openalpr] How to compile openalpr for Mac?

I try to compile openalpr on my MacBook Pro. Below is the note.


0. Test environment

• OS X EI Capitan (v10.11.2)
• tesseract v3.0.4
• openalpr v2.2.0
• opencv v3.0.0

1. Download source

$ git clone https://github.com/openalpr/openalpr.git$ cd openalpr/src
$ mkdir build
$ cd build

2. Install Tesseract (https://code.google.com/p/tesseract-ocr/)

$ wget http://www.leptonica.com/source/leptonica-1.73.tar.gz
$ tar xvf leptonica-1.73.tar.gz
$ cd leptonica-1.73
$ ./configure CC=/usr/bin/clang
$ make
$ sudo make install 

$ cd ~/openalpr
$ git clone https://github.com/tesseract-ocr/tesseract.git tesseract-ocr
$ cd tesseract-ocr/
$ git tag -l $ git checkout tags/3.04.00
$ ./autogen.sh
$ ./configure CXX=/usr/bin/clang++ --with-extra-includes=/usr/local/include --with-extra-libraries=/usr/local/lib
$ make
$ sudo make install

3. Install OpenCV, I used OpenCV v3.0.0 that I already installed.

http://albert-oma.blogspot.tw/2015/08/how-to-install-opencv-in-mac-os.html

4. Install openalpr

$ cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr/local -DCMAKE_INSTALL_SYSCONFDIR:PATH=/etc -DCMAKE_MACOSX_RPATH=true
$ make
$ sudo make install

5. Test

$ wget http://i.imgur.com/pjukRD0.jpg -O lp.jpg
$ alpr lp.jpg

FAQ:

1. Compile error about "undeclared identifier 'ENTER_KEY_ONE' and 'ENTER_KEY_TWO'"Referece

 https://github.com/openalpr/openalpr/blob/master/src/misc_utilities/classifychars.cpp, you will find these 2 definitions are missing for __APPLE__ platform. So you need just add below 2 lines, and it will pass the compilation.
const int ENTER_KEY_ONE = 13;
const int ENTER_KEY_TWO = 10;

2. How to generate test license plate images?

method1. download from here.
method2. use openalpr deamon to capture from a real camera or streaming server.

Reference:

1. https://github.com/openalpr/openalpr/wiki/Compilation-instructions-(OS-X)
2. http://www.vision.caltech.edu/html-files/archive.html

[Openalpr] How to cross compilation openalpr for ARM?

Recently, I survey the open source of license plate recognition. The project "openalpr" seems a good option. I reference the Compilation-instructions-(Ubuntu-Linux),  and try to run the program on arm based linux. Below is my memo.

[OpenCV] Cross compilation for ARM based Linux systems (static)

本篇記錄編譯 OpenCV (static) 的過程。

[OpenCV] 鏡頭校正 Calibration

OpenCV 已經內建鏡頭校正的範例程式，並且提供了許多範例圖片，3.0版本更針對魚眼鏡頭提供了新的函數。這些功能還挺好玩的，以下作一記錄

[OpenCV] OpenCV for iOS

對於 iOS 上如何使用 OpenCV，docs.opencv.org 提供了很多參考文件。
以下對自己的測試過程，作一記錄

1. 可以直接取得 OpenCV framework，或是自行編譯 OpenCV

可至此處 http://sourceforge.net/projects/opencvlibrary/files/opencv-ios/ 直接下載。

本次測試，我選擇自行編譯，步驟如下

[OpenCV] FAQ

此處收集自己使用 OpenCV時遇到的問題與解決方法


1. 沒有 link zlib，錯誤訊息如下

persistence.cpp:(.text.cvOpenFileStorage+0x4a8): undefined reference to `gzrewind'
persistence.cpp:(.text.cvOpenFileStorage+0x844): undefined reference to `gzopen'
persistence.cpp:(.text.cvOpenFileStorage+0xa98): undefined reference to `gzclose'
persistence.cpp:(.text.cvOpenFileStorage+0xcee): undefined reference to `gzgets' 

解法: 自行編譯compile zlib 或是找到可用的 zlib，之後加上 -lzlib 再次編譯即可

[OpenCV] How to install OpenCV in Mac OS

安裝過程摘要

1. download latest opencv package from  http://opencv.org/

$ wget https://github.com/Itseez/opencv/archive/3.0.0.zip