From a16c0c0d7810c8c7212959b48ec57203f46a9f05 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Tue, 23 Mar 2021 18:50:39 +0000
Subject: [PATCH] set mct more carefully

---
 libvips/foreign/jp2ksave.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/libvips/foreign/jp2ksave.c b/libvips/foreign/jp2ksave.c
index 62b78c04..9559ce1a 100644
--- a/libvips/foreign/jp2ksave.c
+++ b/libvips/foreign/jp2ksave.c
@@ -37,9 +37,6 @@
  */
 
 /* TODO
- *
- * - we will have 0.5 pixels if the image width or height is odd and chroma
- *   subsampling is on ... this will cause at least read out of bounds.
  *
  * - could support tiff-like depth parameter
  *
@@ -624,14 +621,9 @@ vips_foreign_save_jp2k_build( VipsObject *object )
 		break;
 	}
 
-	if( jp2k->downsample ) {
+	if( jp2k->downsample ) 
 		jp2k->save_as_ycc = TRUE;
 
-		/* MCT does not work with subsample.
-		 */
-		jp2k->parameters.tcp_mct = FALSE;
-	}
-
 	/* CIELAB etc. do not seem to be well documented.
 	 */
 	switch( save->ready->Type ) {
@@ -717,7 +709,8 @@ vips_foreign_save_jp2k_build( VipsObject *object )
 
 	/* Makes three band images smaller, somehow.
 	 */
-	jp2k->parameters.tcp_mct = save->ready->Bands == 3 ? 1 : 0;
+	jp2k->parameters.tcp_mct = 
+		(save->ready->Bands == 3 && !jp2k->downsample) ? 1 : 0;
 
 	/* Lossy mode.
 	 */