Node Opencv Addon

Opencv Node Addon

Opencv 安裝使用

• 下載Opencv安裝包: http://opencv.org/releases.html

• 解壓進入Opencv目錄

• 編譯Opencv(須要cmake)

mkdir release
cd release
cmake -G "Unix Makefiles" .. (爲Unix 系統生成Makefile，Mac OSX是基於Unix的。未安裝cmake 能夠經過Homebrew安裝，未安裝Homebrew需安裝Homebrew）
make

• 安裝Opencv

make install

• 安裝完成的目錄

/usr/local/lib (Opencv庫文件)
/usr/local/include (Opencv頭文件）
/usr/local/share/ (Opencv xml配置文件)

• 使用Opencv(C++ Version)

  • 編寫CMakeLists.txt文件

    project( ORBFeatureAndCompare ) // 項目的名稱
    cmake_minimum_required(VERSION 2.8) // cmake的版本要求
    find_package( OpenCV REQUIRED ) // 查找對應的Opencv依賴庫
    find_package(Boost COMPONENTS log log_setup thread filesystem system) // 查找對應的Boost依賴庫(下文出現Boost的安裝方法)
    add_executable( ORBFeatureAndCompare ORBFeatureAndCompare )  // 指定可運行的文件
    // 引入對應的依賴庫文件的位置
    target_link_libraries(ORBFeatureAndCompare
        ${OpenCV_LIBS}
        ${Boost_LOG_SETUP_LIBRARY}
        ${Boost_LOG_LIBRARY}
        ${Boost_FILESYSTEM_LIBRARY}
        ${Boost_THREAD_LIBRARY}
        ${Boost_SYSTEM_LIBRARY}
    )

  • 編寫Opencv的cpp文件

    //必要的頭文件
    #include <opencv2/core/core.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/imgproc/imgproc.hpp>
    #include <opencv2/features2d/features2d.hpp>
    #include <boost/filesystem.hpp>
    #include <boost/filesystem/fstream.hpp>
    #include <iostream>
    #include <fstream>
    #include <cstring>
    #include <iterator>
    #include <vector>
    
    using namespace boost::filesystem;  
    namespace newfs = boost::filesystem;
    using namespace cv;
    using namespace std;
    
    int main () {
      ....
      return 0;
    }

  • 建立一個images(其餘命名均可以)的資源文件夾

    cd images
    cmake ..
    make
    ./ORBFeatureAndCompare //編譯出的可執行程序

安裝使用Boost進行數據序列化

• 下載Boost安裝包: https://dl.bintray.com/boosto...

• 解壓進入Boost目錄

• 編譯安裝Boost

./bootstrap.sh
./b2

• 引入Boost庫進行數據序列化,一樣是在CmakeList中引入文件路徑, 在cpp文件中使用

封裝cpp程序爲Node Addon

• 依賴安裝

  • 全局安裝node-gyp

  • 本地安裝nan

• 編寫binding.gyp

  {
    "targets": [
    {
      "target_name": "feature",
      "sources": [ "./src/feature.cc" ],
      "include_dirs": [
        "<!(node -e \"require('nan')\")",
        "/usr/local/include/boost",
        "/usr/local/include/opencv2"
      ],
      "conditions": [
        [ "OS==\"linux\" or OS==\"freebsd\" or OS==\"openbsd\" or OS==\"solaris\" or OS==\"aix\"", {
          }
        ],
        ["OS==\"mac\"", {
            "libraries": [
              "/usr/local/lib/libboost_log_setup-mt.dylib",
              "/usr/local/lib/libboost_log-mt.dylib",
              "/usr/local/lib/libboost_filesystem-mt.dylib",
              "/usr/local/lib/libboost_thread-mt.dylib",
              "/usr/local/lib/libboost_system-mt.dylib",
              "/usr/local/lib/libopencv_core.3.2.0.dylib",
              "/usr/local/lib/libopencv_highgui.3.2.0.dylib",
              "/usr/local/lib/libopencv_imgproc.3.2.0.dylib",
              "/usr/local/lib/libopencv_features2d.3.2.0.dylib"
            ]
          }
        ]
      ]
    }
    ]
  }

• 編寫node c++ 插件

#include <node.h>
#include <nan.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/features2d/features2d.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
#include <iostream>
#include <fstream>
#include <string>
#include <iterator>
#include <vector>

using namespace boost::filesystem;
namespace newfs = boost::filesystem;
using namespace v8;
using namespace std;

vector<uchar> matToString(cv::Mat descriptorMat) {
  vector<uchar> buf;
  imencode(".png", descriptorMat, buf);
  return buf;
}

vector<uchar> descriptorMat(cv::Mat image) {
  vector<cv::KeyPoint> keyPoint;
  cv::Ptr<cv::ORB> orb = cv::ORB::create(4000, 1.2f, 8, 31, 0, 2,             cv::ORB::HARRIS_SCORE, 31, 20);
  orb->detect(image, keyPoint);
  cv::Mat descriptorMat;
  orb->compute(image, keyPoint, descriptorMat);
  return matToString(descriptorMat);
}

void imageFeature(const FunctionCallbackInfo<Value>& args) {
  Isolate* isolate = args.GetIsolate();
  if (args.Length() < 1) {
    isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "Wrong number of arguments")));
    return;
  }
  if (!args[0]->IsString()) {
    isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "Wrong arguments")));
    return;
  }
  String::Utf8Value pathValue(Local<String>::Cast(args[0]));
  string path = string(*pathValue);
  cv::Mat image = cv::imread(path, 1);
  if (image.empty()) {
    isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "Input image error")));
    return;
  }
  vector<uchar> descriptorString = descriptorMat(image);
  Local<Object> buf = Nan::NewBuffer(descriptorString.size()).ToLocalChecked();
  uchar* data = (uchar*) node::Buffer::Data(buf);
  memcpy(data, &descriptorString[0], descriptorString.size());
  v8::Local<v8::Object> globalObj = Nan::GetCurrentContext()->Global();
  v8::Local<v8::Function> bufferConstructor = v8::Local<v8::Function>::Cast(globalObj->Get(Nan::New<String>("Buffer").ToLocalChecked()));
  v8::Local<v8::Value> constructorArgs[3] = {buf, Nan::New<v8::Integer>((unsigned)descriptorString.size()), Nan::New<v8::Integer>(0)};
  v8::Local<v8::Object> actualBuffer = bufferConstructor->NewInstance(3, constructorArgs);
  args.GetReturnValue().Set(actualBuffer);
}

int bfMatcherCompare (cv::Mat &descriptors1, cv::Mat &descriptors2) {
  cv::BFMatcher matcher(cv::NORM_HAMMING);
  vector<cv::DMatch> matches;
  matcher.match(descriptors1, descriptors2, matches);
  double max_dist = 0;
  double min_dist = 100;
  /*
  for (int i = 0; i < descriptors1.rows; i++)
  {
    double dist = matches[i].distance;
    if (dist < min_dist)
      min_dist = dist;
    if (dist > max_dist)
      max_dist = dist;
  }
  vector<cv::DMatch> good_matches;
  for (int i = 0; i < descriptors1.rows; i++)
  {
    if (matches[i].distance < 3 * min_dist)
      good_matches.push_back(matches[i]);
  }
  return good_matches.size();
  */
  for (int i = 0; i < descriptors1.rows; i++) {
    double dist = matches[i].distance;
    if (dist < min_dist) {
      min_dist = dist;
    }
    if (dist > max_dist) {
      max_dist = dist;
    }
  }
  std::vector<cv::DMatch> good_matches;
  double good_matches_sum = 0.0;

  for (int i = 0; i < descriptors1.rows; i++) {
    double distance = matches[i].distance;
    if (distance <= std::max(2 * min_dist, 0.02)) {
      good_matches.push_back(matches[i]);
      good_matches_sum += distance;
    }
  }
  return (double) good_matches_sum / (double) good_matches.size();
}

void similarity(const FunctionCallbackInfo<Value>& args) {
  Isolate* isolate = args.GetIsolate();
  Local<Object> arg1 = args[0]->ToObject();
  int size1 = args[1]->NumberValue();
  Local<Object> arg2 = args[2]->ToObject();
  int size2 = args[3]->NumberValue();
  if (args.Length() < 4) {
    isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "Wrong number of arguments")));
    return;
  }
  uchar*buffer1 = (uchar*) node::Buffer::Data(arg1);
  std::vector<uchar> vec1(buffer1, buffer1 +  (unsigned int) size1);
  cv::Mat img_decode1;
  img_decode1 = cv::imdecode(vec1, CV_8U);
  uchar*buffer2 = (uchar*) node::Buffer::Data(arg2);
  std::vector<uchar> vec2(buffer2, buffer2 +  (unsigned int) size2);
  cv::Mat img_decode2;
  img_decode2 = cv::imdecode(vec2, CV_8U);
  int similarity = bfMatcherCompare(img_decode1, img_decode2);
  args.GetReturnValue().Set(similarity);
}

void init(Local<Object> exports, Local<Object> module) {
  NODE_SET_METHOD(exports, "imageFeature", imageFeature);
  NODE_SET_METHOD(exports, "similarity", similarity);
}

NODE_MODULE(addon, init)

• 編寫Js文件

const feature = require('./build/Release/feature');

exports.getImageFeature = (filePath) => {
  return feature.imageFeature(filePath).toString('utf8');
};

exports.getImageSimilarity = (descriptor1, descriptor2) => {
  let matBuffer1 = Buffer.from(descriptor1);
  let matBuffer2 = Buffer.from(descriptor2);
  return feature.similarity(matBuffer1, matBuffer1.length, matBuffer2, matBuffer2.length);
};

• 編譯運行

node-gyp configure build
node test.js