compute negatives

main.go

@@ -132,7 +132,7 @@ func doSingleImage(f string, c config, s stats) stats {
 	s.StartingBytes += uint64(st.Size())
 	decrease:=st.Size() - stt.Size()
 	diff := ((float64(decrease) / float64(st.Size())) * 100)
-	if uint(diff) > c.Diff {
+	if diff > float64(c.Diff) {
 		// Would replace
 		if c.Replace {
 			err = os.Rename(f, "imageoptimizer.replacetmp")