From 536c5752fe944f6288c87c773dcee74420865b65 Mon Sep 17 00:00:00 2001
From: Young_X <YangX92@hotmail.com>
Date: Sat, 8 Sep 2018 14:36:12 +0800
Subject: [PATCH 2/2] only read/write TIFFTAG_GROUP3OPTIONS or
 TIFFTAG_GROUP4OPTIONS if compression is COMPRESSION_CCITTFAX3 or
 COMPRESSION_CCITTFAX4

---
 tools/pal2rgb.c | 18 +++++++++++++++++-
 tools/tiff2bw.c | 18 +++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/tools/pal2rgb.c b/tools/pal2rgb.c
index 7a57800..01e9dab 100644
--- a/tools/pal2rgb.c
+++ b/tools/pal2rgb.c
@@ -391,7 +391,23 @@ cpTags(TIFF* in, TIFF* out)
 {
     struct cpTag *p;
     for (p = tags; p < &tags[NTAGS]; p++)
-	cpTag(in, out, p->tag, p->count, p->type);
+    {
+        if( p->tag == TIFFTAG_GROUP3OPTIONS )
+        {
+            uint16 compression;
+            if( !TIFFGetField(in, TIFFTAG_COMPRESSION, &compression) ||
+                    compression != COMPRESSION_CCITTFAX3 )
+                continue;
+        }
+        if( p->tag == TIFFTAG_GROUP4OPTIONS )
+        {
+            uint16 compression;
+            if( !TIFFGetField(in, TIFFTAG_COMPRESSION, &compression) ||
+                    compression != COMPRESSION_CCITTFAX4 )
+                continue;
+        }
+        cpTag(in, out, p->tag, p->count, p->type);
+    }
 }
 #undef NTAGS
 
diff --git a/tools/tiff2bw.c b/tools/tiff2bw.c
index dad54af..0c53015 100644
--- a/tools/tiff2bw.c
+++ b/tools/tiff2bw.c
@@ -452,7 +452,23 @@ cpTags(TIFF* in, TIFF* out)
 {
     struct cpTag *p;
     for (p = tags; p < &tags[NTAGS]; p++)
-	cpTag(in, out, p->tag, p->count, p->type);
+    {
+        if( p->tag == TIFFTAG_GROUP3OPTIONS )
+        {
+            uint16 compression;
+            if( !TIFFGetField(in, TIFFTAG_COMPRESSION, &compression) ||
+                    compression != COMPRESSION_CCITTFAX3 )
+                continue;
+        }
+        if( p->tag == TIFFTAG_GROUP4OPTIONS )
+        {
+            uint16 compression;
+            if( !TIFFGetField(in, TIFFTAG_COMPRESSION, &compression) ||
+                    compression != COMPRESSION_CCITTFAX4 )
+                continue;
+        }
+        cpTag(in, out, p->tag, p->count, p->type);
+    }
 }
 #undef NTAGS
 
-- 
2.17.2

