diff --git a/Configuration.md b/Configuration.md
index 3a19ccc..73178d9 100644
--- a/Configuration.md
+++ b/Configuration.md
@@ -79,6 +79,7 @@ const config: Config = {
                              // if just one is set, second one is scaled automatically
                              // if both are set, values are used as-is
     return: true,            // return processed canvas imagedata in result
+    flip: false,             // flip input as mirror image
     brightness: 0,           // range: -1 (darken) to 1 (lighten)
     contrast: 0,             // range: -1 (reduce contrast) to 1 (increase contrast)
     sharpness: 0,            // range: 0 (no sharpening) to 1 (maximum sharpening)