Add min brightness threshold to LED targets

New per-target property: when effective output brightness
(max pixel value × device/source brightness) falls below
the threshold, LEDs turn off completely. Useful for cutting
dim flicker in audio-reactive and ambient setups.

Threshold slider (0–254) in target editor, badge on card,
hot-swap to running processors, persisted in storage.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/core/processing/processor_manager.py

@@ -317,6 +317,7 @@ class ProcessorManager:
         keepalive_interval: float = 1.0,
         state_check_interval: int = DEFAULT_STATE_CHECK_INTERVAL,
         brightness_value_source_id: str = "",
+        min_brightness_threshold: int = 0,
     ):
         """Register a WLED target processor."""
         if target_id in self._processors:
@@ -332,6 +333,7 @@ class ProcessorManager:
             keepalive_interval=keepalive_interval,
             state_check_interval=state_check_interval,
             brightness_value_source_id=brightness_value_source_id,
+            min_brightness_threshold=min_brightness_threshold,
             ctx=self._build_context(),
         )
         self._processors[target_id] = proc

server/src/wled_controller/core/processing/wled_target_processor.py

@@ -36,6 +36,7 @@ class WledTargetProcessor(TargetProcessor):
         keepalive_interval: float = 1.0,
         state_check_interval: int = 30,
         brightness_value_source_id: str = "",
+        min_brightness_threshold: int = 0,
         ctx: TargetContext = None,
     ):
         super().__init__(target_id, ctx)
@@ -45,6 +46,7 @@ class WledTargetProcessor(TargetProcessor):
         self._state_check_interval = state_check_interval
         self._css_id = color_strip_source_id
         self._brightness_vs_id = brightness_value_source_id
+        self._min_brightness_threshold = min_brightness_threshold
 
         # Runtime state (populated on start)
         self._led_client: Optional[LEDClient] = None
@@ -210,6 +212,8 @@ class WledTargetProcessor(TargetProcessor):
                 self._keepalive_interval = settings["keepalive_interval"]
             if "state_check_interval" in settings:
                 self._state_check_interval = settings["state_check_interval"]
+            if "min_brightness_threshold" in settings:
+                self._min_brightness_threshold = settings["min_brightness_threshold"]
         logger.info(f"Updated settings for target {self._target_id}")
 
     def update_device(self, device_id: str) -> None:
@@ -581,6 +585,15 @@ class WledTargetProcessor(TargetProcessor):
 
                         cur_brightness = _effective_brightness(device_info)
 
+                        # Min brightness threshold: combine brightness source
+                        # with max pixel value to get effective output brightness.
+                        # If below cutoff → snap to 0 (LEDs off).
+                        _thresh = self._min_brightness_threshold
+                        if _thresh > 0 and cur_brightness > 0:
+                            max_pixel = int(np.max(frame))
+                            if max_pixel * cur_brightness // 255 < _thresh:
+                                cur_brightness = 0
+
                         # Zero-brightness suppression: if output is black and
                         # the last sent frame was also black, skip sending.
                         if cur_brightness <= 1 and _prev_brightness <= 1 and has_any_frame: