--- c/xpdf/pdftopng.cc
+++ c/xpdf/pdftopng.cc
@@ -21,6 +21,8 @@
#include "SplashOutputDev.h"
#include "config.h"
+#define INCHESPERMETER 39.37007874
+
static int firstPage = 1;
static int lastPage = 0;
static int resolution = 150;
@@ -261,6 +263,9 @@ static void setupPNG(png_structp *png, png_infop *pngInfo, FILE *f,
png_set_IHDR(*png, *pngInfo, bitmap->getWidth(), bitmap->getHeight(),
bitDepth, colorType, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+ png_set_pHYs(*png, *pngInfo, resolution*INCHESPERMETER, resolution*INCHESPERMETER,
+ PNG_RESOLUTION_METER);
+
png_write_info(*png, *pngInfo);
}