Better png save

vips.h

@@ -125,7 +125,7 @@ vips_jpegsave_go(VipsImage *in, void **buf, size_t *len, int strip, int quality,
 int
 vips_pngsave_go(VipsImage *in, void **buf, size_t *len)
 {
-  return vips_pngsave_buffer(in, buf, len, NULL);
+  return vips_pngsave_buffer(in, buf, len, "filter", VIPS_FOREIGN_PNG_FILTER_NONE, NULL);
 }
 
 int