PDF::Writer：ImageInfo

everyday Ruby 
require 'pdf/writer'

f = open('images/chunkybacon.jpg')
image = f.read

i = PDF::Writer::Graphics::ImageInfo.new(image)
p i.instance_variables
p [i.format, i.height, i.width, i.bits, i.channels, i.info]

で、

["@channels", "@width", "@info", "@bits", "@format", "@height", "@top", "@data"]
["JPEG", 229, 265, 8, 3, {"APP-224"=>"JFIF\000\001\001\000\000\001\000\001\000\000"}]