画像にロゴを埋め込むRubyスクリプト（RMagickを使う）

#!/usr/bin/env ruby

require 'fileutils'
require 'RMagick'
 
if ARGV.length != 1
  abort("Usage: add_logo filename")
end

LOGO_IMAGE = 'add_logo.png'

image_filename = ARGV[0]
image = Magick::Image.read(image_filename).first
logo = Magick::Image.read(LOGO_IMAGE).first
image.composite!(logo, Magick::SouthWestGravity, Magick::OverCompositeOp)
image.write(image_filename)