Ruby: Create image thumbnails using OS X sips

gistfile1.rb

thumb_width = 117
thumb_height = 141

raise ArgumentError, 'No images given. You must supply at least one image to process' if ARGV.empty?

ARGV.each do |image|
	if File.file?(image)
		width = `sips -g pixelWidth "#{image}"`.match(/pixelWidth: \d+$/im).to_s.match(/\d+/).to_s.to_i
		height = `sips -g pixelHeight "#{image}"`.match(/pixelHeight: \d+$/im).to_s.match(/\d+/).to_s.to_i
		
		if width > height
			target = height	
		else
			target = width
		end
		
		`sips -c #{target} #{target} "#{image}"`
		`sips -z #{thumb_height} #{thumb_width} "#{image}"`
	end	
end