From 47a4bf83a4354740359f4c535a3ccd0f9238bb66 Mon Sep 17 00:00:00 2001
From: Adam Williamson <awilliam@redhat.com>
Date: Tue, 10 Jan 2017 16:12:51 -0800
Subject: [PATCH] Only byte-swap 16-bit PNGs on little-endian (#7792)

_png has some code that unconditionally byte-swaps 16-bit PNG
data (which is, per the spec, stored in big-endian order). This
isn't appropriate on a big-endian platform, though: this swap
being done unconditionally breaks the handling of 16-bit PNGs
on big-endian platforms (e.g. Fedora ppc64), as reported in
this swap or not.
---
 src/_png.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/_png.cpp b/src/_png.cpp
index f5c25deeb..06e4b8754 100644
--- a/src/_png.cpp
+++ b/src/_png.cpp
@@ -532,10 +532,12 @@ static PyObject *_read_png(PyObject *filein, bool float_result)
         png_set_shift(png_ptr, sig_bit);
     }
 
+#if NPY_BYTE_ORDER == NPY_LITTLE_ENDIAN
     // Convert big endian to little
     if (bit_depth == 16) {
         png_set_swap(png_ptr);
     }
+#endif
 
     // Convert palletes to full RGB
     if (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE) {
-- 
2.11.0