convert image with image_science

convert.rb

#! /usr/bin/ruby
# usage: ruby convert.rb icon.jpg png
require 'rubygems'
require 'image_science'

if ARGV.length == 2
  source_file = ARGV.first
  target_extension = ARGV.last
  target_file = source_file.sub /[\w\d]+$/, target_extension
  
  ImageScience::with_image(source_file) do |img|
    img.save(target_file)
  end
end