diff --git a/code/perception/src/traffic_light_detection/src/traffic_light_detection/traffic_light_inference.py b/code/perception/src/traffic_light_detection/src/traffic_light_detection/traffic_light_inference.py
index ada59c5f..cb3d9e5c 100644
--- a/code/perception/src/traffic_light_detection/src/traffic_light_detection/traffic_light_inference.py
+++ b/code/perception/src/traffic_light_detection/src/traffic_light_detection/traffic_light_inference.py
@@ -64,7 +64,7 @@ def __call__(self, img):
         else:
             out = self.model(img)
         _, prediction = torch.max(out.data, 1)
-        return prediction.item()
+        return (prediction.item(), out.data.cpu().numpy())
 
 
 # main function for testing purposes
diff --git a/code/perception/src/traffic_light_node.py b/code/perception/src/traffic_light_node.py
index 6f67b5b1..00034bab 100755
--- a/code/perception/src/traffic_light_node.py
+++ b/code/perception/src/traffic_light_node.py
@@ -1,5 +1,8 @@
 #!/usr/bin/env python3
 
+from datetime import datetime
+import threading
+from time import sleep
 from ros_compatibility.node import CompatibleNode
 import ros_compatibility as roscomp
 from rospy.numpy_msg import numpy_msg
@@ -18,6 +21,9 @@ def __init__(self, name, **kwargs):
         self.role_name = self.get_param("role_name", "hero")
         self.side = self.get_param("side", "Center")
         self.classifier = TrafficLightInference(self.get_param("model", ""))
+        self.last_info_time: datetime = None
+        self.last_state = None
+        threading.Thread(target=self.auto_invalidate_state).start()
 
         # publish / subscribe setup
         self.setup_camera_subscriptions()
@@ -38,14 +44,38 @@ def setup_traffic_light_publishers(self):
             qos_profile=1
         )
 
+    def auto_invalidate_state(self):
+        while True:
+            sleep(1)
+
+            if self.last_info_time is None:
+                continue
+
+            if (datetime.now() - self.last_info_time).total_seconds() >= 2:
+                msg = TrafficLightState()
+                msg.state = 0
+                self.traffic_light_publisher.publish(msg)
+                self.last_info_time = None
+
     def handle_camera_image(self, image):
-        result = self.classifier(self.bridge.imgmsg_to_cv2(image))
+        result, data = self.classifier(self.bridge.imgmsg_to_cv2(image))
+
+        if data[0][0] > 1e-15 and data[0][3] > 1e-15 or \
+           data[0][0] > 1e-10 or data[0][3] > 1e-10:
+            return  # too uncertain, may not be a traffic light
 
-        # 1: Green, 2: Red, 4: Yellow, 0: Unknown
-        msg = TrafficLightState()
-        msg.state = result if result in [1, 2, 4] else 0
+        state = result if result in [1, 2, 4] else 0
+        if self.last_state == state:
+            # 1: Green, 2: Red, 4: Yellow, 0: Unknown
+            msg = TrafficLightState()
+            msg.state = state
+            self.traffic_light_publisher.publish(msg)
+        else:
+            self.last_state = state
 
-        self.traffic_light_publisher.publish(msg)
+        # Automatically invalidates state (state=0) in auto_invalidate_state()
+        if state != 0:
+            self.last_info_time = datetime.now()
 
     def run(self):
         self.spin()
diff --git a/code/perception/src/vision_node.py b/code/perception/src/vision_node.py
index e9681a4c..938ee669 100755
--- a/code/perception/src/vision_node.py
+++ b/code/perception/src/vision_node.py
@@ -191,14 +191,19 @@ def process_traffic_lights(self, prediction, cv_image, image_header):
         indices = (prediction.boxes.cls == 9).nonzero().squeeze().cpu().numpy()
         indices = np.asarray([indices]) if indices.size == 1 else indices
 
-        min_x = 550
-        max_x = 700
-        min_prob = 0.35
+        max_y = 360  # middle of image
+        min_prob = 0.30
 
         for index in indices:
             box = prediction.boxes.cpu().data.numpy()[index]
 
-            if box[0] < min_x or box[2] > max_x or box[4] < min_prob:
+            if box[4] < min_prob:
+                continue
+
+            if (box[2] - box[0]) * 1.5 > box[3] - box[1]:
+                continue  # ignore horizontal boxes
+
+            if box[1] > max_y:
                 continue
 
             box = box[0:4].astype(int)
diff --git a/doc/06_perception/13_traffic_light_detection.md b/doc/06_perception/13_traffic_light_detection.md
index c627e3cf..68a061c6 100644
--- a/doc/06_perception/13_traffic_light_detection.md
+++ b/doc/06_perception/13_traffic_light_detection.md
@@ -35,3 +35,22 @@ This method sets up a publisher for the traffic light state. It publishes to the
 
 This method is called whenever a new image message is received. It performs traffic light detection by using `traffic_light_inference.py` on the image and publishes the result.
 The result is a `TrafficLightState` message where the state is set to the detected traffic light state (1 for green, 2 for red, 4 for yellow, 0 for unknown).
+
+## Filtering of images
+
+### Vision Node
+
+Objects, which are detected as traffic light by the RTDETR-X model (or others), must fulfill the following criterias to be published:
+
+- At least a 30% (0.30) certainty/probablity of the classification model
+- More than 1.5x as tall (height) as it is wide (width)
+- Above 360px (upper half of the 1280x720 image)
+
+### Traffic Light Node
+
+Objects, which are published by the Vision Node, are further filtered by the following criterias:
+
+- Classification probabilities of "Unknown" and "Side" are either both below 1e-10 or one of both are below 1e-15
+- "Side" is treated as "Unknown"
+- Valid states (Red, Green, Yellow) must be present at least twice in a row to be actually published
+- A state decays (state=0; "Unknown") after 2 seconds if there is no new info in the meantime