From 9026b81439251925a6cc3b15cde71e2938dd0aa7 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@gmail.com>
Date: Fri, 28 Aug 2015 22:54:17 +1000
Subject: [PATCH] Check that images are L mode in ImageMorph methods

---
 PIL/ImageMorph.py        |  9 +++++++++
 Tests/test_imagemorph.py | 10 +++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/PIL/ImageMorph.py b/PIL/ImageMorph.py
index 6f92e9e67..44a7e8c04 100644
--- a/PIL/ImageMorph.py
+++ b/PIL/ImageMorph.py
@@ -198,6 +198,9 @@ class MorphOp(object):
         if self.lut is None:
             raise Exception('No operator loaded')
 
+        if image.mode != 'L':
+            raise Exception('Image must be binary, meaning it must use mode L')
+            return
         outimage = Image.new(image.mode, image.size, None)
         count = _imagingmorph.apply(
             bytes(self.lut), image.im.id, outimage.im.id)
@@ -212,6 +215,9 @@ class MorphOp(object):
         if self.lut is None:
             raise Exception('No operator loaded')
 
+        if image.mode != 'L':
+            raise Exception('Image must be binary, meaning it must use mode L')
+            return
         return _imagingmorph.match(bytes(self.lut), image.im.id)
 
     def get_on_pixels(self, image):
@@ -220,6 +226,9 @@ class MorphOp(object):
         Returns a list of tuples of (x,y) coordinates
         of all matching pixels."""
 
+        if image.mode != 'L':
+            raise Exception('Image must be binary, meaning it must use mode L')
+            return
         return _imagingmorph.get_on_pixels(image.im.id)
 
     def load_lut(self, filename):
diff --git a/Tests/test_imagemorph.py b/Tests/test_imagemorph.py
index bbb3ae190..a3d1dd8b1 100644
--- a/Tests/test_imagemorph.py
+++ b/Tests/test_imagemorph.py
@@ -1,5 +1,5 @@
 # Test the ImageMorphology functionality
-from helper import unittest, PillowTestCase
+from helper import unittest, PillowTestCase, hopper
 
 from PIL import Image
 from PIL import ImageMorph
@@ -168,6 +168,14 @@ class MorphTests(PillowTestCase):
         self.assertEqual(len(coords), 4)
         self.assertEqual(tuple(coords), ((2, 2), (4, 2), (2, 4), (4, 4)))
 
+    def test_non_binary_images(self):
+        im = hopper('RGB')
+        mop = ImageMorph.MorphOp(op_name="erosion8")
+
+        self.assertRaises(Exception, lambda: mop.apply(im))
+        self.assertRaises(Exception, lambda: mop.match(im))
+        self.assertRaises(Exception, lambda: mop.get_on_pixels(im))
+
 
 if __name__ == '__main__':
     unittest.main()