The history of this patch is unknown: it existed when ImageMagick was
migrated to Userland.

--- ImageMagick-6.8.3/coders/png.c.~1~	2013-02-15 04:48:48.000000000 -0800
+++ ImageMagick-6.8.3/coders/png.c	2015-02-10 20:39:14.131500401 -0800
@@ -100,6 +100,10 @@
 
 #include "png.h"
 #include "zlib.h"
+#if PNG_LIBPNG_VER >= 10400
+#define trans_values trans_color
+#define trans trans_alpha
+#endif
 
 /* ImageMagick differences */
 #define first_scene scene