Little image optimization script

optimize-images.rb

#!/usr/bin/env ruby

# Debian pkg dependencies:
# - pngcrush
# - libjpeg-progs
# - imagemagick

# Usage: optimize-images graphic1.png photo1.jpeg bash-glob-exp1

require "fileutils"

ARGV.each do |pattern|
  Dir[File.expand_path(pattern)].each do |path|
    dirname = File.dirname(path)
    dest = File.join(dirname, "_#{File.basename(path)}")

    type = `file #{path}`[/: ([^,]+)/, 1]
    success = case type
              when /JPEG/
                system("jpegtran -copy none -optimize -outfile #{dest} #{path}")
              when /PNG/
                system("pngcrush -rem alla -reduce -q #{path} #{dest}")
              when /GIF/
                # only convert non-animated GIFs to PNG8
                if `identify -format %m #{path}` == "GIF"
                  basename = File.basename(path, File.extname(path))
                  dest = File.join(dirname, "#{basename}.png")

                  if system("convert #{path} #{dest}")
                    src = dest
                    dest = File.join(dirname, "_#{File.basename(src)}")
                    system("pngcrush -rem alla -reduce #{src} #{dest}")
                  end
                end
              end

    FileUtils.mv(dest, path) if success
  end
end