diff --git a/script/device/Image.py b/script/device/Image.py
index f5fc791..a11e5e1 100644
--- a/script/device/Image.py
+++ b/script/device/Image.py
@@ -139,8 +139,8 @@ class Image(DeviceBase, Readable):
         if threshold4 is not None:
             self.threshold4 = threshold4
 
-    def init_threshold():
-        self.threshold1, tself.threshold2, self.threshold3, self.threshold4 = self.pixel.threshold1, self.pixel.threshold2, self.pixel.threshold3, self.pixel.threshold4
+    def init_threshold(self):
+        self.threshold1, self.threshold2, self.threshold3, self.threshold4 = self.pixel.threshold1, self.pixel.threshold2, self.pixel.threshold3, self.pixel.threshold4
 
 
 class ReadableImage(ReadableMatrix):