capistrano task for optimize images after asset:precompile using optipng and jpegoptim

gistfile1.rb

namespace :image_compression do
  desc 'Optimize images with optipng and jpegoptim'
  task :process do

    # Check for optipng
    if (!`which optipng`.empty? rescue false) # rescue on environments without `which` (windows)

      # Crush all .png files inplace
      run "find #{shared_path}/assets/ -type f -name '*.png' -print0 | xargs -0 optipng -quiet -o7 "
    else
      logger.info "WARNING: optipng not found. Skipping..."
    end

    # Check for jpegoptim
    if (!`which jpegoptim`.empty? rescue false) # rescue on environments without `which` (windows)

      # Crush all .jpg files in place
      run "find #{shared_path}/assets/ -type f -name '*.jpg' -print0 | xargs -0 -n1 sh -c 'jpegoptim --quiet --strip-all $0'"

    else
      logger.info "WARNING: jpegoptim not found. Skipping..."
    end
  end

  # Set to run after assets:precompile task
  after "deploy:assets:precompile", "image_compression:process"
end