How to validate whether an image url is valid or not

image_validate.rb

module ImgageValidate
  module_function

  def url_exist?(url)
    uri = URI.parse(url)
    Net::HTTP.start(uri.host, uri.port) do |http|
      Net::HTTP.start(uri.host, uri.port) do |http|
        response = http.head(uri.path)
        case response
        when Net::HTTPSuccess, Net::HTTPRedirection
          case response.content_type
          when "image/png", "image/gif", "image/jpeg", "image/jpg"
            true
          else
            false
          end
        else
          false
        end
      end
    end
  end
end

ImgageValidate.url_exist?("http://s3.amazonaws.com/podknife-production/uploads/podcast/uploaded_cover_img/462/thumb_512-1.jpg") 

# => false
https://github.com/carrierwaveuploader/carrierwave/wiki/how-to:-validate-the-url-for-remote-uploads
Or

MiniMagick::Image.open("http://s3.amazonaws.com/podknife-production/uploads/podcast/uploaded_cover_img/462/thumb_512-1.jpg")