cloud_vision.rb

require 'base64'
require 'json'
require 'net/http'
require 'uri'
require 'open-uri'

VISION_API_URL = "https://vision.googleapis.com/v1/images:annotate"
API_KEY        = "foobarbazhogefuga"
URL            = "#{VISION_API_URL}?key=#{API_KEY}"
INPUT_IMG_FILE = 'http://blog-imgs-42-origin.fc2.com/k/o/t/kotomona/20101125183059615.jpg'

begin
  uri           = URI.parse(URL)
  https         = Net::HTTP.new(uri.host, uri.port)
  https.use_ssl = true

  req                 = Net::HTTP::Post.new(uri.request_uri)
  req["Content-Type"] = "application/json"
  param               = {
    "requests" =>
    [
      {
        "image" =>
        {
          "content" => Base64.strict_encode64(open(INPUT_IMG_FILE).read)
        },
        "features" =>
        [
          {
            "type"       => "LABEL_DETECTION",
            "maxResults" => 10
          },
          {
            "type"       => "TEXT_DETECTION",
            "maxResults" => 10
          }
        ]
      }
    ]
  }
  req.body = param.to_json
  res      = https.request(req)

  case res
  when Net::HTTPSuccess
    puts res.body
    json = JSON.load(res.body)

  else
    res.error!
  end
rescue => e
  puts "error = #{e.message}"
end