Update README.md

Author: KingsMentor

README.md

@@ -79,3 +79,10 @@ On `onDestroy`, do not forget to clean cached bitmap and tell  `BlurHash` to can
         blurHash.clean()
     }
 ```
+
+### What is the `punch` parameter in some of these implementations?
+
+It is a parameter that adjusts the contrast on the decoded image. 1 means normal, smaller values will make the effect more subtle,
+and larger values will make it stronger. This is basically a design parameter, which lets you adjust the look.
+
+Technically, what it does is scale the AC components up or down.