From 53de81f0a187fe5b0ede558d65db8dd25cae6f16 Mon Sep 17 00:00:00 2001
From: Moriyoshi Koizumi <mozo@mozo.jp>
Date: Thu, 6 Nov 2014 12:18:41 +0900
Subject: [PATCH] The optimization algorithm is only applicable to the image of
 mode="P".

---
 PIL/GifImagePlugin.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/PIL/GifImagePlugin.py b/PIL/GifImagePlugin.py
index 0b154f417..35dbc5c68 100644
--- a/PIL/GifImagePlugin.py
+++ b/PIL/GifImagePlugin.py
@@ -433,7 +433,7 @@ def getheader(im, palette=None, info=None):
 
     usedPaletteColors = paletteBytes = None
 
-    if optimize:
+    if im.mode == "P" and optimize:
         usedPaletteColors = []
 
         # check which colors are used