From 364586738de74d26d7ed9af6419f3cf7c83bbc54 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sat, 25 May 2019 16:24:42 +1000
Subject: [PATCH] Do not down-convert if image is LA when showing with PNG
 format

---
 src/PIL/ImageShow.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/PIL/ImageShow.py b/src/PIL/ImageShow.py
index bbd841db77c..ecf1792779a 100644
--- a/src/PIL/ImageShow.py
+++ b/src/PIL/ImageShow.py
@@ -71,7 +71,9 @@ def show(self, image, **options):
             # FIXME: auto-contrast if max() > 255?
         else:
             base = Image.getmodebase(image.mode)
-        if base != image.mode and image.mode != "1" and image.mode != "RGBA":
+        if not (base == image.mode or
+                image.mode in ("1", "RGBA") or
+                (self.format == "PNG" and image.mode == "LA")):
             image = image.convert(base)
 
         return self.show_image(image, **options)