diff --git a/lib/prawn/core/filters.rb b/lib/prawn/core/filters.rb
index 9dc828ebe..f4299fb45 100644
--- a/lib/prawn/core/filters.rb
+++ b/lib/prawn/core/filters.rb
@@ -11,118 +11,6 @@
 module Prawn
   module Core
     module Filters
-      module ASCIIHexDecode
-        def self.encode(stream)
-          result = ''
-
-          stream.each_byte do |byte|
-            result << byte.to_s(16)
-          end
-
-          result + '>'
-        end
-
-        def self.decode(stream)
-          result = ''
-
-          data = stream.gsub(/[\x00\x09\x0a\x0c\x0d\x20]/, '') # Whitespaces are ignored
-          if data =~ />/
-            data = data.split('>')[0] # Decode up untill EOD marker
-            if data.length.odd?
-              data << '0'
-            end
-          end
-
-          if data =~ /[^0-9a-fA-F]/
-            raise "ASCIIHexDecode filter encountered unexpected data in stream"
-          end
-
-          data.scan(/../).each do |hex|
-            result << hex.to_i(16)
-          end
-
-          result
-        end
-      end
-
-      module ASCII85Decode
-        require 'strscan'
-
-        def self.encode(stream)
-          return '' if stream.empty?
-
-          padding = 4 - stream.bytesize % 4
-
-          # Extract big-endian integers
-          groups = (stream + ("\0" * padding)).unpack('N*')
-
-          # Encode
-          groups.map! do |group|
-            if group == 0
-              'z'
-            else
-              tmp = ""
-              5.times do
-                tmp << ((group % 85) + 33).chr
-                group /= 85
-              end
-              tmp.reverse
-            end
-          end
-
-          # We can't use the z-abbreviation if we're going to cut off padding
-          if (padding > 0) && (groups.last == 'z')
-            groups[-1] = '!!!!!'
-          end
-
-          # Cut off the padding
-          groups[-1] = groups[-1][0..(4 - padding)]
-
-          groups.join('') + '~>'
-        end
-
-        def self.decode(stream)
-          data = stream.gsub(/[\x00\x09\x0a\x0c\x0d\x20]/, '') # Whitespaces are ignored
-          if data =~ /~>/
-            data = data.split('~>')[0] # Decode up until EOD marker
-          end
-
-          s = StringScanner.new(data)
-
-          padding = 0
-          result = ''
-
-          until s.eos?
-            group = s.scan(/z|[^z]{0,5}/)
-            if group == 'z'
-              group = '!!!!!'
-            end
-
-            if group.length < 5
-              if s.eos?
-                padding = 5 - group.length
-                group << 'u' * padding
-              else
-                raise "Malformed data at #{s.pos}"
-              end
-            end
-
-            word = 0
-
-            group.unpack('C*').each_with_index do |byte, i|
-              word += (byte - 33) * 85 ** (4 - i)
-            end
-            result << [word].pack('N')
-
-            if padding > 0
-              result = result[0...-padding]
-            end
-          end
-
-          result
-        end
-      end
-
       module FlateDecode
         def self.encode(stream, params = nil)
           Zlib::Deflate.deflate(stream)
diff --git a/spec/filters_spec.rb b/spec/filters_spec.rb
index 4ea866844..96e7e5cd0 100644
--- a/spec/filters_spec.rb
+++ b/spec/filters_spec.rb
@@ -3,8 +3,6 @@
 require File.join(File.expand_path(File.dirname(__FILE__)), "spec_helper")
 
 FILTERS = {
-  :ASCIIHexDecode => {'test' => "74657374>"},
-  :ASCII85Decode  => {'test' => "FCfN8!~>"},
   :FlateDecode    => {'test' => ruby_19 { "x\x9C+I-.\x01\x00\x04]\x01\xC1".force_encoding(Encoding::ASCII_8BIT) } || "x\x9C+I-.\x01\x00\x04]\x01\xC1" },
   :DCTDecode      => {'test' => "test"}
 }