module WeixinAuthorize::Api::Media

def covert(uploader)
  # image process
  unless (uploader.file.content_type =~ /image/).nil?
    if !jpep?(uploader.file)
      require "mini_magick"
      # covert to jpeg
      image = MiniMagick::Image.open(uploader.path)
      image.format("jpg")
      uploader.cache!(File.open(image.path))
      image.destroy! # remove /tmp from MinMagick generate
    end
  end
  uploader
end