From 17c31027059cb618fad6f7edd3947ac6b2780107 Mon Sep 17 00:00:00 2001
From: Vadim Pisarevsky <no@email>
Date: Fri, 28 Oct 2011 02:22:11 +0000
Subject: [PATCH] improved png compression ratio (ticket #1452)

---
 modules/highgui/src/grfmt_png.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/highgui/src/grfmt_png.cpp b/modules/highgui/src/grfmt_png.cpp
index d0e2680384..045530a977 100644
--- a/modules/highgui/src/grfmt_png.cpp
+++ b/modules/highgui/src/grfmt_png.cpp
@@ -366,7 +366,7 @@ bool  PngEncoder::write( const Mat& img, const vector<int>& params )
                         png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_FILTER_SUB);
                         png_set_compression_level(png_ptr, Z_BEST_SPEED);
                     }
-                    png_set_compression_strategy(png_ptr, Z_HUFFMAN_ONLY);
+                    png_set_compression_strategy(png_ptr, Z_FILTERED);
 
                     png_set_IHDR( png_ptr, info_ptr, width, height, depth == CV_8U ? 8 : 16,
                         channels == 1 ? PNG_COLOR_TYPE_GRAY :