diff --git a/src/main.rs b/src/main.rs
index 90b9121..2e6973d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -80,6 +80,10 @@ impl State {
                     self.image = imageops::rotate90(&self.image);
                     return self.allocate_image();
                 }
+                Key::Character("i") => {
+                    imageops::invert(&mut self.image);
+                    return self.allocate_image();
+                }
 
                 // ignore unused keys
                 _ => {}