From 0b3036454c9b73d650fd187de457d1377bbc1b55 Mon Sep 17 00:00:00 2001
From: Martin Packman <gzlist@googlemail.com>
Date: Mon, 17 Sep 2018 16:30:42 +0100
Subject: [PATCH] Give correct extrema for I;16 format images

Currently gives None for a 16 bit greyscale image rather than the
true min and max values in the 0-65536 range. The internal
ImagingGetProjection function already supports I;16 but the
_getextrema needs to know to unpack the result.
---
 Tests/images/16_bit_noise.tif  | Bin 0 -> 2446 bytes
 Tests/test_image_getextrema.py |   8 ++++++++
 src/_imaging.c                 |   5 +++++
 3 files changed, 13 insertions(+)
 create mode 100644 Tests/images/16_bit_noise.tif

diff --git a/Tests/images/16_bit_noise.tif b/Tests/images/16_bit_noise.tif
new file mode 100644
index 0000000000000000000000000000000000000000..19180638efa88ebf827c78a7ed5e4a112815e10b
GIT binary patch
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literal 0
HcmV?d00001

diff --git a/Tests/test_image_getextrema.py b/Tests/test_image_getextrema.py
index 0b0c31b86..9783141a3 100644
--- a/Tests/test_image_getextrema.py
+++ b/Tests/test_image_getextrema.py
@@ -1,3 +1,4 @@
+from PIL import Image
 from helper import unittest, PillowTestCase, hopper
 
 
@@ -19,6 +20,13 @@ class TestImageGetExtrema(PillowTestCase):
             extrema("RGBA"), ((0, 255), (0, 255), (0, 255), (255, 255)))
         self.assertEqual(
             extrema("CMYK"), (((0, 255), (0, 255), (0, 255), (0, 0))))
+        self.assertEqual(extrema("I;16"), (0, 255))
+
+    def test_true_16(self):
+        im = Image.open("Tests/images/16_bit_noise.tif")
+        self.assertEqual(im.mode, 'I;16')
+        extrema = im.getextrema()
+        self.assertEqual(extrema, (106, 285))
 
 
 if __name__ == '__main__':
diff --git a/src/_imaging.c b/src/_imaging.c
index 3acbdb01c..9620a0691 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -1998,6 +1998,7 @@ _getextrema(ImagingObject* self, PyObject* args)
         UINT8 u[2];
         INT32 i[2];
         FLOAT32 f[2];
+        UINT16 s[2];
     } extrema;
     int status;
 
@@ -2013,6 +2014,10 @@ _getextrema(ImagingObject* self, PyObject* args)
             return Py_BuildValue("ii", extrema.i[0], extrema.i[1]);
         case IMAGING_TYPE_FLOAT32:
             return Py_BuildValue("dd", extrema.f[0], extrema.f[1]);
+        case IMAGING_TYPE_SPECIAL:
+            if (strcmp(self->image->mode, "I;16") == 0) {
+                return Py_BuildValue("HH", extrema.s[0], extrema.s[1]);
+            }
         }
 
     Py_INCREF(Py_None);