Script that allows you to run some manipulations on images in a threaded way. This script uses celluloid to create actors that manipulate the pictures by resizing them and adding a border.

convert_images.rb

require "celluloid"

DIRECTORY = "PUT DIRECTORY HERE"
PICTURE_EXTENSIONS = %w{ jpg png }
BORDER_SIZE = "3x3"
BORDER_COLOR = "black"
NEW_SIZE = 1200
DO_AUTO_ORIENT = false
WORKERS = 8

class PictureManipulator
  include Celluloid

  def initialize
  end

  def manipulate(pic)
    puts "Start converting #{pic}..."
    %x{ convert #{pic} -resize #{NEW_SIZE} #{pic} }

    %x{ convert #{pic} -shave #{BORDER_SIZE} -bordercolor #{BORDER_COLOR} -border #{BORDER_SIZE} #{pic} }

    puts "Finished converting #{pic}"
  end
end

pool = PictureManipulator.pool(size: WORKERS)

futures = []
PICTURE_EXTENSIONS.concat PICTURE_EXTENSIONS.map(&:upcase)


Dir.chdir(DIRECTORY) do
  Dir.glob("*.{#{PICTURE_EXTENSIONS.join(",")}}").each do |file|
    futures << pool.future.manipulate("#{DIRECTORY}/#{file}")
  end
end

futures.map(&:value)