Detect blank pages in PDF

detect-blankpages.rb

#! /usr/bin/env ruby

require "open3"

out, status = Open3.capture2e("gs -o /dev/null -sDEVICE=bbox '#{ARGV[0]}'")

array = out.rstrip.split(/\r?\n/).map {|line| line.chomp }

count = 0
blankpage_list = []
array.each do |i|
  if i.include?("0 0 0 0")
    pageindex = count - 1
    blankpage_list << array[pageindex]
  end
  count += 1
end

puts array[3]
puts "blank page = #{blankpage_list.length} pages"
p blankpage_list