Compress images larger than 5MB

compress_large_images.rb

require 'mini_magick'
require 'fileutils'

TARGET_DIR = Pathname(ARGV[0] || '.')
BACKUP_DIR = TARGET_DIR.join('backup')
IMAGE_EXT = %w(jpg jpeg png gif bmp tiff webp heic avif)
SIZE_LIMIT = 5 * 1024 * 1024 # MB

class Image
  attr_reader :size, :quality

  def initialize(filepath, quality: nil)
    @filepath = filepath
    @size = @filepath.size
    @quality = quality
  end

  def mb
    (@size / 1024.0 / 1024.0).round(2)
  end

  def compress!(size_limit)
    image, quality = nil, nil

    (1..100).bsearch do |m|
      image = MiniMagick::Image.open(@filepath)
      image.format('jpg')

      quality = 100 - m
      image.quality(quality)

      image.size <= SIZE_LIMIT
    end

    image.write(@filepath)

    Image.new(@filepath, quality: quality)
  end

  private

  def image
    @image ||= MiniMagick::Image.open(@filepath)
  end
end

TARGET_DIR.glob('*').each do |filepath|
  next unless filepath.file?
  next unless IMAGE_EXT.include?(filepath.extname.delete('.').downcase)
  next unless filepath.size >= SIZE_LIMIT

  BACKUP_DIR.mkdir unless BACKUP_DIR.exist?
  backup_path = BACKUP_DIR.join(File.basename(filepath))
  FileUtils.cp(filepath, BACKUP_DIR.join(filepath.basename)) unless backup_path.exist?

  image = Image.new(filepath)
  compressed_image = image.compress!(SIZE_LIMIT)

  puts("#{filepath}: #{image.mb} MB -> #{compressed_image.mb} MB")
end