From 09c457240219c4ebababd8862f8bd847bb58b8f2 Mon Sep 17 00:00:00 2001
From: Morgan Hardwood <bugs@londonlight.org>
Date: Wed, 7 Feb 2018 17:10:57 +0100
Subject: [PATCH] Fix corrupt 32-bit compressed TIFF

Match endianness of pixel data with endianness of Exif metadata when
saving compressed 32-bit float TIFF.
Fixes #4377
---
 rtengine/imageio.cc | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/rtengine/imageio.cc b/rtengine/imageio.cc
index 0e404fa91..306c95892 100644
--- a/rtengine/imageio.cc
+++ b/rtengine/imageio.cc
@@ -1438,14 +1438,14 @@ int ImageIO::saveTIFF (Glib::ustring fname, int bps, bool uncompressed)
         }
     }
 
-    if (iptcdata) {
-        rtexif::Tag iptcTag(nullptr, rtexif::lookupAttrib (rtexif::ifdAttribs, "IPTCData"));
-        iptcTag.initLongArray((char*)iptcdata, iptclen);
 #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__
         bool needsReverse = exifRoot && exifRoot->getOrder() == rtexif::MOTOROLA;
 #else
         bool needsReverse = exifRoot && exifRoot->getOrder() == rtexif::INTEL;
 #endif
+    if (iptcdata) {
+        rtexif::Tag iptcTag(nullptr, rtexif::lookupAttrib (rtexif::ifdAttribs, "IPTCData"));
+        iptcTag.initLongArray((char*)iptcdata, iptclen);
         if (needsReverse) {
             unsigned char *ptr = iptcTag.getValue();
             for (int a = 0; a < iptcTag.getCount(); ++a) {
@@ -1471,15 +1471,13 @@ int ImageIO::saveTIFF (Glib::ustring fname, int bps, bool uncompressed)
     TIFFSetField (out, TIFFTAG_ROWSPERSTRIP, height);
     TIFFSetField (out, TIFFTAG_BITSPERSAMPLE, bps);
     TIFFSetField (out, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
-    TIFFSetField (out, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_UINT);
     TIFFSetField (out, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB);
-    TIFFSetField (out, TIFFTAG_COMPRESSION, uncompressed ? COMPRESSION_NONE : COMPRESSION_DEFLATE);
+    TIFFSetField (out, TIFFTAG_COMPRESSION, uncompressed ? COMPRESSION_NONE : COMPRESSION_ADOBE_DEFLATE);
     TIFFSetField (out, TIFFTAG_SAMPLEFORMAT, bps == 32 ? SAMPLEFORMAT_IEEEFP : SAMPLEFORMAT_UINT);
 
     if (!uncompressed) {
         TIFFSetField (out, TIFFTAG_PREDICTOR, bps == 32 ? PREDICTOR_FLOATINGPOINT : PREDICTOR_HORIZONTAL);
     }
-
     if (profileData) {
         TIFFSetField (out, TIFFTAG_ICCPROFILE, profileLength, profileData);
     }
@@ -1487,6 +1485,17 @@ int ImageIO::saveTIFF (Glib::ustring fname, int bps, bool uncompressed)
     for (int row = 0; row < height; row++) {
         getScanline (row, linebuffer, bps);
 
+        if(needsReverse && !uncompressed && bps == 32) {
+            for(int i = 0; i < lineWidth; i += 4) {
+                char temp = linebuffer[i];
+                linebuffer[i] = linebuffer[i + 3];
+                linebuffer[i + 3] = temp;
+                temp = linebuffer[i + 1];
+                linebuffer[i + 1] = linebuffer[i + 2];
+                linebuffer[i + 2] = temp;
+            }
+        }
+
         if (TIFFWriteScanline (out, linebuffer, row, 0) < 0) {
             TIFFClose (out);
             delete [] linebuffer;