From cd21272b34268f767972d8c297480c0b2653db4c Mon Sep 17 00:00:00 2001
From: ShadelessFox <yanuari.channel@gmail.com>
Date: Sun, 17 Jul 2022 17:11:52 +0300
Subject: [PATCH] Fix BC6 block decoder

---
 src/libImaging/BcnDecode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libImaging/BcnDecode.c b/src/libImaging/BcnDecode.c
index 22b36eb7acc..9e830cf072c 100644
--- a/src/libImaging/BcnDecode.c
+++ b/src/libImaging/BcnDecode.c
@@ -750,8 +750,10 @@ decode_bc6_block(rgb32f *col, const UINT8 *src, int sign) {
         }
     }
     if (info->tr) { /* apply deltas */
-        for (i = 3; i < numep; i++) {
+        for (i = 3; i < numep; i += 3) {
             endpoints[i] = (endpoints[i] + endpoints[0]) & mask;
+            endpoints[i + 1] = (endpoints[i + 1] + endpoints[1]) & mask;
+            endpoints[i + 2] = (endpoints[i + 2] + endpoints[2]) & mask;
         }
         if (sign) {
             for (i = 3; i < numep; i += 3) {