From 49617bad8e85ea2ac967c064d2428ed58e7a129f Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Mon, 22 Aug 2022 19:55:43 +1000
Subject: [PATCH] Do not use CCITTFaxDecode filter if libtiff is not available

---
 Tests/test_file_pdf.py    |  2 +-
 src/PIL/PdfImagePlugin.py | 33 ++++++++++++++++++---------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/Tests/test_file_pdf.py b/Tests/test_file_pdf.py
index 310619fb255..5371c52d171 100644
--- a/Tests/test_file_pdf.py
+++ b/Tests/test_file_pdf.py
@@ -43,7 +43,7 @@ def test_monochrome(tmp_path):
 
     # Act / Assert
     outfile = helper_save_as_pdf(tmp_path, mode)
-    assert os.path.getsize(outfile) < 5000
+    assert os.path.getsize(outfile) < (5000 if features.check("libtiff") else 15000)
 
 
 def test_greyscale(tmp_path):
diff --git a/src/PIL/PdfImagePlugin.py b/src/PIL/PdfImagePlugin.py
index 181a05b8d26..404759a7fcb 100644
--- a/src/PIL/PdfImagePlugin.py
+++ b/src/PIL/PdfImagePlugin.py
@@ -25,7 +25,7 @@
 import os
 import time
 
-from . import Image, ImageFile, ImageSequence, PdfParser, __version__
+from . import Image, ImageFile, ImageSequence, PdfParser, __version__, features
 
 #
 # --------------------------------------------------------------------
@@ -130,20 +130,23 @@ def _save(im, fp, filename, save_all=False):
             width, height = im.size
 
             if im.mode == "1":
-                filter = "CCITTFaxDecode"
-                bits = 1
-                params = PdfParser.PdfArray(
-                    [
-                        PdfParser.PdfDict(
-                            {
-                                "K": -1,
-                                "BlackIs1": True,
-                                "Columns": width,
-                                "Rows": height,
-                            }
-                        )
-                    ]
-                )
+                if features.check("libtiff"):
+                    filter = "CCITTFaxDecode"
+                    bits = 1
+                    params = PdfParser.PdfArray(
+                        [
+                            PdfParser.PdfDict(
+                                {
+                                    "K": -1,
+                                    "BlackIs1": True,
+                                    "Columns": width,
+                                    "Rows": height,
+                                }
+                            )
+                        ]
+                    )
+                else:
+                    filter = "DCTDecode"
                 colorspace = PdfParser.PdfName("DeviceGray")
                 procset = "ImageB"  # grayscale
             elif im.mode == "L":