From cfcd819246f8eb1b1f1e7d43b7ba91c94329f14b Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Tue, 4 Nov 2014 09:38:21 +0000
Subject: [PATCH] better default resolution for png load

see

https://github.com/lovell/sharp/issues/96
---
 ChangeLog                 |  3 +++
 libvips/foreign/vipspng.c | 10 +++++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a09cafd4..90c64d68 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+4/11/14 started 7.42.0
+- better default resolution for png load
+
 25/7/14 started 7.41.0
 - start working on --disable-deprecated
 - fix pngload with libpng >1.6.1
diff --git a/libvips/foreign/vipspng.c b/libvips/foreign/vipspng.c
index e5cad2a7..d4149fdd 100644
--- a/libvips/foreign/vipspng.c
+++ b/libvips/foreign/vipspng.c
@@ -339,15 +339,15 @@ png2vips_header( Read *read, VipsImage *out )
 	/* If we're an INTEL byte order machine and this is 16bits, we need
 	 * to swap bytes.
 	 */
-	if( bit_depth > 8 && !vips_amiMSBfirst() )
+	if( bit_depth > 8 && 
+		!vips_amiMSBfirst() )
 		png_set_swap( read->pPng );
 
-	/* Get resolution. I'm not sure what we should do for UNKNOWN, since
-	 * vips is always pixels/mm.
+	/* Get resolution. Default to 72 pixels per inch, the usual png value. 
 	 */
 	unit_type = PNG_RESOLUTION_METER;
-	res_x = 1000;
-	res_y = 1000;
+	res_x = (72 / 2.54 * 100);
+	res_y = (72 / 2.54 * 100);
 	png_get_pHYs( read->pPng, read->pInfo, &res_x, &res_y, &unit_type );
 	switch( unit_type ) {
 	case PNG_RESOLUTION_METER: