Retina image converter

converter.rb

require 'rubygems'
require 'RMagick'

convertedCnt = 0

ARGV.each do |filename|
    img_type = File.extname(filename).downcase
    if (img_type==".png")||(img_type==".jpg")||(img_type==".tif")
        ext = File.extname(filename)
        base = File.basename(filename,ext)
        dir = File.dirname(filename)

		next if dir == "converted"

        if /^#{dir}\/(.+)@2x(#{ext})$/ =~ filename
            exportdir = dir+"/converted"
            exportname = exportdir+"/"+$1+$2

            folderFlag = true
            if !FileTest.exist?(exportdir)
                Dir.mkdir(exportdir)
            else
                if FileTest.file?(exportdir) 
                    puts "Error!: #{exportdir} exists."
                    folderFlag = false
                end
            end

            if folderFlag
                original = Magick::Image.read(filename).first
                width = original.columns
                height = original.rows

                # Resize
                image = original.resize(width/2,height/2,filter=Magick::LanczosFilter,0.9)
                image.write(exportname)

                convertedCnt += 1
            end
        end
    end
end
puts "Converted #{convertedCnt} images."

This code has been forked from http://hamken100.blogspot.jp/2012/05/automator-retina2.html