From a2cb304f62e060fc8f8145aafc31143fd941dc9e Mon Sep 17 00:00:00 2001
From: Hin-Tak Leung <htl10@users.sourceforge.net>
Date: Mon, 8 May 2017 21:19:16 +0100
Subject: [PATCH] use PNG as intermediate format for viewing

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

diff --git a/PIL/ImageShow.py b/PIL/ImageShow.py
index 33f059d74..d03dc4627 100644
--- a/PIL/ImageShow.py
+++ b/PIL/ImageShow.py
@@ -115,7 +115,7 @@ if sys.platform == "win32":
 elif sys.platform == "darwin":
 
     class MacViewer(Viewer):
-        format = "BMP"
+        format = "PNG"
 
         def get_command(self, file, **options):
             # on darwin open returns immediately resulting in the temp
@@ -142,6 +142,8 @@ else:
         return None
 
     class UnixViewer(Viewer):
+        format = "PNG"
+
         def show_file(self, file, **options):
             command, executable = self.get_command_ex(file, **options)
             command = "(%s %s; rm -f %s)&" % (command, quote(file),