From 00ddda303a247f01c208a0a5b9c0252ffef2a809 Mon Sep 17 00:00:00 2001
From: Joris Van Damme <joris.at.lebbeke@skynet.be>
Date: Sat, 29 Sep 2007 10:34:37 +0000
Subject: [PATCH] tif_dirread.c: Fixed bad behaviour of strip chopping on
 uncompressed subsampled images.

---
 ChangeLog             |  8 ++++++++
 libtiff/tif_dirread.c | 33 +++++++++++++++++++++++----------
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b8a6a943..e13babb7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2007-09-29  Joris Van Damme  <joris.at.lebbeke@skynet.be>
+
+	* tif_dirread.c: Strip chopping interfered badly with uncompressed 
+	subsampled images because it tried to divide subsamples rowblock, leading 
+	to all sorts of errors throughout the library for these images. Fixed by 
+	making strip chopping divide in row counts that are multiple of vertical 
+	subsampling value.
+
 2007-09-28  Joris Van Damme  <joris.at.lebbeke@skynet.be>
 
 	* tif_dirread.c: Logical cast working around compiler warning
diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index 8992b27b..3b3ab4b3 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -1,4 +1,4 @@
-/* $Id: tif_dirread.c,v 1.133 2007-09-27 17:38:57 joris Exp $ */
+/* $Id: tif_dirread.c,v 1.134 2007-09-29 10:34:38 joris Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -5255,9 +5255,11 @@ static void
 ChopUpSingleUncompressedStrip(TIFF* tif)
 {
 	register TIFFDirectory *td = &tif->tif_dir;
-	uint64 bytecount = td->td_stripbytecount[0];
-	uint64 offset = td->td_stripoffset[0];
-	uint64 rowbytes = TIFFVTileSize64(tif, 1), stripbytes;
+	uint64 bytecount;
+	uint64 offset;
+	uint32 rowblock;
+	uint64 rowblockbytes;
+	uint64 stripbytes;
 	uint32 strip;
 	uint64 nstrips64;
 	uint32 nstrips32;
@@ -5265,16 +5267,27 @@ ChopUpSingleUncompressedStrip(TIFF* tif)
 	uint64* newcounts;
 	uint64* newoffsets;
 
+	bytecount = td->td_stripbytecount[0];
+	offset = td->td_stripoffset[0];
+	assert(td->td_planarconfig == PLANARCONFIG_CONTIG);
+	if ((td->td_photometric == PHOTOMETRIC_YCBCR)&&
+	    (!isUpSampled(tif)))
+		rowblock = td->td_ycbcrsubsampling[1];
+	else
+		rowblock = 1;
+	rowblockbytes = TIFFVTileSize64(tif, rowblock);
 	/*
 	 * Make the rows hold at least one scanline, but fill specified amount
 	 * of data if possible.
 	 */
-	if (rowbytes > STRIP_SIZE_DEFAULT) {
-		stripbytes = rowbytes;
-		rowsperstrip = 1;
-	} else if (rowbytes > 0 ) {
-		rowsperstrip = (uint32) (STRIP_SIZE_DEFAULT / rowbytes);
-		stripbytes = rowbytes * rowsperstrip;
+	if (rowblockbytes > STRIP_SIZE_DEFAULT) {
+		stripbytes = rowblockbytes;
+		rowsperstrip = rowblock;
+	} else if (rowblockbytes > 0 ) {
+		uint32 rowblocksperstrip;
+		rowblocksperstrip = (uint32) (STRIP_SIZE_DEFAULT / rowblockbytes);
+		rowsperstrip = rowblocksperstrip * rowblock;
+		stripbytes = rowblocksperstrip * rowblockbytes;
 	}
 	else
 	    return;