Edit Exif data (change date taken)

shift_time.rb

require 'mini_exiftool'
# modified mini_exiftool/examples/shift_time.rb
# MiniExiftool.command = 'path/to/exiftool.exe'
delta = 60*60*2 # 2 hour

# Dir.chdir("./path/to/photos") do
  Dir.foreach(".") do |f|
    if f =~ /.+\.JPG$/ then
      begin
        photo = MiniExiftool.new(f)
      rescue MiniExiftool::Error => e
        $stderr.puts e.message
        exit -1
      end
      org_time = photo['DateTimeOriginal']
      photo['DateTimeOriginal'] = org_time + delta
      saved = photo.save
      if saved then
        fmt = '%Y-%m-%d %H:%M:%S'
        puts "#{f} changed: #{org_time.strftime(fmt)} -> #{photo['DateTimeOriginal'].strftime(fmt)}"
      else
        puts "#{f} could not be changed"
      end
    end
  end
# end