diff --git a/PyPDF2/filters.py b/PyPDF2/filters.py
index 86aa1dd..20eb0f5 100644
--- a/PyPDF2/filters.py
+++ b/PyPDF2/filters.py
@@ -34,7 +34,9 @@ Implementation of stream filters for PDF.
 __author__ = "Mathieu Fenniak"
 __author_email__ = "biziqe@mathieu.fenniak.net"
 
-from .utils import PdfReadError, ord_, chr_
+import math
+
+from .utils import PdfReadError, ord_, chr_, paethPredictor
 from sys import version_info
 if version_info < ( 3, 0 ):
     from cStringIO import StringIO
@@ -137,6 +139,18 @@ class FlateDecode(object):
                     elif filterByte == 2:
                         for i in range(1, rowlength):
                             rowdata[i] = (rowdata[i] + prev_rowdata[i]) % 256
+                    elif filterByte == 3:
+                        for i in range(1, rowlength):
+                            left = rowdata[i-1] if i > 1 else 0
+                            floor = math.floor(left + prev_rowdata[i])/2
+                            rowdata[i] = (rowdata[i] + int(floor)) % 256
+                    elif filterByte == 4:
+                        for i in range(1, rowlength):
+                            left = rowdata[i - 1] if i > 1 else 0
+                            up = prev_rowdata[i]
+                            up_left = prev_rowdata[i - 1] if i > 1 else 0
+                            paeth = paethPredictor(left, up, up_left)
+                            rowdata[i] = (rowdata[i] + paeth) % 256
                     else:
                         # unsupported PNG filter
                         raise PdfReadError("Unsupported PNG filter %r" % filterByte)
diff --git a/PyPDF2/utils.py b/PyPDF2/utils.py
index 718a875..6b536a0 100644
--- a/PyPDF2/utils.py
+++ b/PyPDF2/utils.py
@@ -293,3 +293,17 @@ def hexStr(num):
 
 
 WHITESPACES = [b_(x) for x in [' ', '\n', '\r', '\t', '\x00']]
+
+
+def paethPredictor(left, up, up_left):
+    p = left + up - up_left
+    dist_left = abs(p - left)
+    dist_up = abs(p - up)
+    dist_up_left = abs(p - up_left)
+
+    if dist_left <= dist_up and dist_left <= dist_up_left:
+        return left
+    elif dist_up <= dist_up_left:
+        return up
+    else:
+        return up_left