From 8ba90206ef111b91af32ae93fad31563d49be755 Mon Sep 17 00:00:00 2001
From: Andrii Ryzhkov <andrii.ryzhkov@pm.me>
Date: Mon, 4 May 2026 22:04:21 +0200
Subject: [PATCH] Add TIFFTAG_PREVIEWCOLORSPACE fallback for libtiff < 4.6

---
 src/imageio/imageio_dng.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/imageio/imageio_dng.c b/src/imageio/imageio_dng.c
index 4ba764a8e4bf..5da1fa350213 100644
--- a/src/imageio/imageio_dng.c
+++ b/src/imageio/imageio_dng.c
@@ -36,6 +36,11 @@
 #include <wchar.h>
 #endif
 
+// fallback for libtiff < 4.6
+#ifndef TIFFTAG_PREVIEWCOLORSPACE
+#define TIFFTAG_PREVIEWCOLORSPACE 50970
+#endif
+
 // DNG uses SRATIONAL / RATIONAL for matrix and WB tags. libtiff accepts
 // these as float/double arrays and handles the conversion; we just pass
 // the values as double