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如何使用OpenCV及Python搭建图片缩略图服务器-创新互联

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应用程序进程树, 默认 Poolboy 中初始化10个用于处理图片的 Python 工作进程(Worker)

如何使用OpenCV及Python搭建图片缩略图服务器

首先安装OpenCV需要的工具包

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

brew install python

brew tap homebrew/science

brew install opencv

sudo pip install numpy

sudo pip install matplotlib

使用 Homebrew 的 Python 版本, 而不是 Mac OS X 系统自带的 Python

alias python='/usr/local/bin/python'

创建 Elixir 项目

?  mix new opencv_thumbnail_server --sup

* creating README.md

* creating .gitignore

* creating mix.exs

* creating config

* creating config/config.exs

* creating lib

* creating lib/opencv_thumbnail_server.ex

* creating test

* creating test/test_helper.exs

* creating test/opencv_thumbnail_server_test.exs

 

Your Mix project was created successfully.

You can use "mix" to compile it, test it, and more:

 

    cd opencv_thumbnail_server

    mix test

 

Run "mix help" for more commands.

Elixir 模块

require Logger

defmodule OpencvThumbnailServer do

  use Application

  def start(_type, _args) do

    Logger.info "Start opencv thumbnail server"

    OpencvThumbnailServer.Supervisor.start_link()

  end

end

defmodule OpencvThumbnailServer.Supervisor do

  use Supervisor

 

  @config Application.get_env :opencv_thumbnail_server, :settings

 

  def start_link() do

    Supervisor.start_link(__MODULE__, [], name: {:global,__MODULE__})

  end

 

  def init([]) do

    pool_options = @config[:poolboy]

    {_, name} = pool_options[:name]

    children = [

      :poolboy.child_spec(name, pool_options, @config[:module_name])

    ]

    supervise(children, strategy: :one_for_all, max_restarts: 1000, max_seconds: 3600)

  end

end

defmodule OpencvThumbnailServer.Worker do

  use GenServer

  @config Application.get_env(:opencv_thumbnail_server, :settings)

 

  def start_link(python_module) do

    GenServer.start_link(__MODULE__, python_module, [])

  end

 

  def call_python(worker, function, args) do

    GenServer.call(worker, {:call_python, function, args}, 10_000)

  end

 

  def init(python_module) do

    IO.puts "Start worker"

    {:ok, pid} = :python.start_link([

      {:python_path, @config[:python_path]},

      {:python, @config[:python]}

    ])

    state = {python_module, pid}

    {:ok, state}

  end

 

  def handle_call({:call_python, function, args}, _from, state) do

    {module, pid} = state

    result = :python.call(pid, module, function, args)

    reply = {:ok, result}

    {:reply, reply, state}

  end

 

  def handle_call(_request, _from, state) do

    {:stop, :error, :bad_call, state}

  end

 

  def handle_info(_msg, {module,py_pid}) do

    {:stop, :error, {module,py_pid}}

  end

 

  def terminate(_reason, {_, py_pid}) do

    :python.stop(py_pid)

    :ok

  end

end

图像处理

获取宽高

# -*- coding: utf-8 -*-

 

import urllib2 as urllib

import numpy as np

import cv2

 

 

def load_image_url(url):

    resp = urllib.urlopen(url)

    buf = resp.read()

    return buf

 

 

def load_image_file(filename):

    image = cv2.imdecode(filename, cv2.IMREAD_COLOR)

    return image

 

def get_photo_sizes():

    return [

        [160, 160],

        [320, 320],

        [640, 640],

        [1060, 1060],

        [1280, 1280]

    ]

def show(buf):

    # print buf

    # x = cv2.imdecode(image, cv2.IMREAD_COLOR)

    # d = cv2.cvtColor(c, cv2.COLOR_RGB2BGR)

    np_ndarray = np.fromstring(buf, dtype=np.uint8)

    x = cv2.imdecode(np_ndarray, cv2.IMREAD_UNCHANGED)

    return cv2.imshow('NBA Image', x)

 

def write(buf):

    nparray = np.fromstring(buf, dtype=np.uint8)

    img = cv2.imdecode(nparray, cv2.IMREAD_UNCHANGED)

    return cv2.imwrite('/tmp/imwrite.png', img)

 

# def get_dimension():

#     url = '/upload/otherpic40/16010642_1200x1000_0.jpg'

#     resp = urllib.urlopen(url)

#     buf = resp.read()

#     x = np.fromstring(buf, dtype=np.uint8)

#     img = cv2.imdecode(x, cv2.IMREAD_UNCHANGED)

#     # height = np.size(img, 0)

#     # width = np.size(img, 1)

#     height, width = image.shape[:2]

#     return (width, height)

 

def get_dimension(buffer):

    # 把原始的二进制图片数据转换为NpArray

    nparray = np.fromstring(buffer, dtype=np.uint8)

    # 把 nparray 转换为 opencv 的图像格式

    image = cv2.imdecode(nparray, cv2.IMREAD_UNCHANGED)

    height, width = image.shape[:2]

    return (width, height)

 

def convert_color():

    url = '/upload/otherpic40/6941baebgw1epzcuv9vmxj20me0hy0u1.jpg'

    resp = urllib.urlopen(url)

    buf = resp.read()

    x = np.fromstring(buf, dtype=np.uint8)

    img = cv2.imdecode(x, cv2.IMREAD_UNCHANGED)

 

if __name__ == '__main__':

    get_dimension()

在 Erlang 和 Python 之间传输二进制数据

Erlang 的binary()数据类型和 Python 之间的映射关系, 在Python 2.x 中二进制数据类型为 str() 表示, Python 3.x 中为 bytes()

buf = resp.read(), 其中变量 buf 的类型为

在 Elixir 我们看的如下的值

Python

{:ok, <<255, 216, 255, 224, 0, 16, 74, 70, 73, 70, 0, 1, 1, 1, 0, 72,

      0, 72, 0, 0, 255, 219, 0, 67, 0, 8, 6, 6, 7, 6, 5, 8, 7, 7, 7,

      9, 9, 8, 10, 12, 20, 13, 12, 11, 11, 12, 25, 18, 19, ...>>}

调用 Python 函数

{:ok, data} = OpencvThumbnailServer.Api.load_image_url("https://segmentfault.com/img/bVwhAW")

OpencvThumbnailServer.Api.get_dimension(data)

{:ok, {800, 431}}

如何使用OpenCV及Python搭建图片缩略图服务器

创建 Python 模块

之前的 Python 图像处理模块可以组织到一个项目中单独维护. 这里使用工具 cookiecutter创建 Python 一个基本的项目骨架, 用于实现缩略图的功能

cookiecutter 可以通过多种方式安装, 包括pip, easy_install, conda, brew

pip install cookiecutter

easy_install cookiecutter

conda install -c https://conda.binstar.org/pydanny cookiecutter

brew install cookiecutter(Mac OS X)

目录结构

?  opencv_thumbnail git:(master) tree

.

├── AUTHORS.rst

├── CONTRIBUTING.rst

├── HISTORY.rst

├── LICENSE

├── MANIFEST.in

├── Makefile

├── README.rst

├── build

│   ├── bdist.macosx-10.11-x86_64

│   └── lib

│       └── opencv_thumbnail

│           ├── __init__.py

│           └── opencv_thumbnail.py

├── dist

│   └── opencv_thumbnail-0.1.0-py2.7.egg

├── docs

│   ├── Makefile

│   ├── authors.rst

│   ├── conf.py

│   ├── contributing.rst

│   ├── history.rst

│   ├── index.rst

│   ├── installation.rst

│   ├── make.bat

│   ├── readme.rst

│   └── usage.rst

├── opencv_thumbnail

│   ├── __init__.py

│   ├── __init__.pyc

│   ├── opencv_thumbnail.py

│   └── opencv_thumbnail.pyc

├── opencv_thumbnail.egg-info

│   ├── PKG-INFO

│   ├── SOURCES.txt

│   ├── dependency_links.txt

│   ├── not-zip-safe

│   └── top_level.txt

├── requirements_dev.txt

├── setup.cfg

├── setup.py

├── tests

│   ├── __init__.py

│   └── test_opencv_thumbnail.py

├── tox.ini

└── travis_pypi_setup.py

 

9 directories, 36 files

API实现

调用需要从 Poolboy 池中取出一个工作进程, 并调用工作进程的call_python, 进程使用完成后返回 Poolboy 进程池, 这里封装一下以简化调用厦门叉车出租公司

defmodule OpencvThumbnailServer.Api do

  alias OpencvThumbnailServer.Worker

 

  def get_dimension(data) do

    worker = :poolboy.checkout(:opencv_thumbnail_server_pool)

    {w, h} = Worker.call_python(worker, :get_dimension, [data])

    :poolboy.checkin(:opencv_thumbnail_server_pool, worker)

    {w, h}

  end

 

  def load_image_url(url) do

    worker = :poolboy.checkout(:opencv_thumbnail_server_pool)

    image_bin = Worker.call_python(worker, :load_image_url, [url])

    :poolboy.checkin(:opencv_thumbnail_server_pool, worker)

    image_bin

  end

end

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