Opt.

counter.c/counter.c

@@ -58,6 +58,7 @@ void counter_create(unsigned long number, FILE *fd) {
     PNG_COMPRESSION_TYPE_BASE,
     PNG_FILTER_TYPE_BASE
   );
+  png_set_compression_level(png, 1);
   png_write_info(png, info);
   png_write_image(png, rows);
   png_write_end(png, info);