DeepLabCut · C-Achard · Jun 24, 2026 · Jun 24, 2026 · Jun 24, 2026 · Jun 24, 2026
diff --git a/dlclivegui/cameras/backends/aravis_backend.py b/dlclivegui/cameras/backends/aravis_backend.py
@@ -52,6 +52,8 @@ def __init__(self, settings):
         self._actual_width: int | None = None
         self._actual_height: int | None = None
         self._actual_fps: float | None = None
+        self._camera_pixel_format: str | None = None
+        self._actual_output_format: str | None = None
 
         self._camera = None
         self._stream = None
@@ -69,6 +71,16 @@ def actual_fps(self) -> float | None:
         """Return the actual frame rate of the camera after opening."""
         return self._actual_fps
 
+    @property
+    def actual_pixel_format(self) -> str | None:
+        """Camera/native pixel format requested/reported for Aravis."""
+        return self._camera_pixel_format or self._pixel_format
+
+    @property
+    def actual_output_format(self) -> str | None:
+        """Current Aravis backend emits BGR uint8 frames."""
+        return self._actual_output_format or "BGR8"
+
     @classmethod
     def is_available(cls) -> bool:
         """Check if Aravis is available on this system."""
@@ -615,10 +627,12 @@ def _configure_pixel_format(self) -> None:
 
             if self._pixel_format in format_map:
                 self._camera.set_pixel_format(format_map[self._pixel_format])
+                self._camera_pixel_format = self._pixel_format
                 LOG.info(f"Pixel format set to '{self._pixel_format}'")
             else:
                 # Try setting as string
                 self._camera.set_pixel_format_from_string(self._pixel_format)
+                self._camera_pixel_format = self._pixel_format
                 LOG.info(f"Pixel format set to '{self._pixel_format}' (from string)")
         except Exception as e:
             LOG.warning(f"Failed to set pixel format '{self._pixel_format}': {e}")

diff --git a/dlclivegui/cameras/backends/basler_backend.py b/dlclivegui/cameras/backends/basler_backend.py
@@ -9,7 +9,7 @@
 
 import numpy as np
 
-from ...config import SINGLE_CAMERA_WORKER_DO_LOG_TIMING, CameraTriggerSettings
+from ...config import BASLER_DO_LOG_TIMING, CameraTriggerSettings
 from ...utils.stats import WorkerTimingStats
 from ..base import CameraBackend, SupportLevel, register_backend
 
@@ -46,6 +46,11 @@ def __init__(self, settings):
         super().__init__(settings)
 
         self._props: dict = settings.properties if isinstance(settings.properties, dict) else {}
+        self._preserve_mono: bool = bool(
+            getattr(settings, "preserve_mono", False) or self.ns.get("preserve_mono", False)
+        )
+        self._camera_pixel_format: str | None = None
+        self._logged_first_frame: bool = False
 
         # Optional fast-start hint for probe workers
         # (may skip StartGrabbing and converter setup for faster capability probing; not suitable for normal capture)
@@ -117,7 +122,7 @@ def __init__(self, settings):
             timing_id,
             logger=LOG,
             log_interval=1.0,
-            enabled=SINGLE_CAMERA_WORKER_DO_LOG_TIMING,
+            enabled=BASLER_DO_LOG_TIMING,
         )
 
     @property
@@ -138,6 +143,24 @@ def actual_exposure(self) -> float | None:
     def actual_gain(self) -> float | None:
         return self._actual_gain
 
+    @property
+    def actual_pixel_format(self) -> str | None:
+        """Camera/native pixel format reported by Basler, e.g. 'Mono8'."""
+        return self._camera_pixel_format
+
+    @property
+    def actual_output_format(self) -> str | None:
+        """Backend output frame format emitted to the app, e.g. 'Mono8' or 'BGR8'."""
+        if not self._camera_pixel_format:
+            return None
+        return "Mono8" if self._should_output_mono() else "BGR8"
+
+    @property
+    def recommended_preserve_mono(self) -> bool | None:
+        if not self._camera_pixel_format:
+            return None
+        return self._is_camera_mono()
+
     @classmethod
     def is_available(cls) -> bool:
         return pylon is not None
@@ -154,6 +177,7 @@ def static_capabilities(cls) -> dict[str, SupportLevel]:
                 "device_discovery": SupportLevel.BEST_EFFORT,
                 "stable_identity": SupportLevel.SUPPORTED,
                 "hardware_trigger": SupportLevel.BEST_EFFORT,
+                "preserve_mono": SupportLevel.SUPPORTED,
             }
         )
         return caps
@@ -180,6 +204,17 @@ def _ensure_mutable_ns(self) -> dict:
             self.settings.properties[self.OPTIONS_KEY] = ns
         return ns
 
+    def _read_camera_pixel_format(self) -> str:
+        pixel_format = self._feature_value(self._feature("PixelFormat"), "")
+        self._camera_pixel_format = str(pixel_format or "")
+        return self._camera_pixel_format
+
+    def _is_camera_mono(self) -> bool:
+        return bool(self._camera_pixel_format and self._camera_pixel_format.startswith("Mono"))
+
+    def _should_output_mono(self) -> bool:
+        return bool(self._preserve_mono and self._is_camera_mono())
+
     @classmethod
     def _enumerate_devices_cls(cls):
         """Enumerate DeviceInfo entries (unit-testable via monkeypatch)."""
@@ -463,6 +498,37 @@ def _configure_frame_rate(self) -> None:
         except Exception:
             self._actual_fps = None
 
+    def _configure_converter(self) -> None:
+        """Configure pypylon image converter.
+
+        Default behavior remains BGR8 for compatibility.
+
+        If preserve_mono=True and the camera PixelFormat is Mono*,
+        return Mono8 frames as 2D arrays to avoid 3x BGR expansion.
+        """
+        if self._camera is None:
+            return
+
+        camera_pixel_format = self._camera_pixel_format or self._read_camera_pixel_format()
+
+        self._converter = pylon.ImageFormatConverter()
+        self._converter.OutputBitAlignment = pylon.OutputBitAlignment_MsbAligned
+
+        if self._should_output_mono():
+            self._converter.OutputPixelFormat = pylon.PixelType_Mono8
+            LOG.info(
+                "[Basler] Converter configured for Mono8 output (camera PixelFormat=%s preserve_mono=%s)",
+                camera_pixel_format,
+                self._preserve_mono,
+            )
+        else:
+            self._converter.OutputPixelFormat = pylon.PixelType_BGR8packed
+            LOG.info(
+                "[Basler] Converter configured for BGR8 output (camera PixelFormat=%s preserve_mono=%s)",
+                camera_pixel_format,
+                self._preserve_mono,
+            )
+
     def open(self) -> None:
         if pylon is None:
             raise RuntimeError("pypylon is required for the Basler backend but is not installed")
@@ -548,6 +614,8 @@ def open(self) -> None:
         except Exception:
             self._actual_gain = None
 
+        self._read_camera_pixel_format()
+
         # ----------------------------
         # Start acquisition (skip for fast probe)
         # ----------------------------
@@ -560,9 +628,7 @@ def open(self) -> None:
                 pass
 
             # Converter BEFORE StartGrabbing
-            self._converter = pylon.ImageFormatConverter()
-            self._converter.OutputPixelFormat = pylon.PixelType_BGR8packed
-            self._converter.OutputBitAlignment = pylon.OutputBitAlignment_MsbAligned
+            self._configure_converter()
 
             # Force stream configuration reset
             try:
@@ -638,6 +704,20 @@ def read(self) -> tuple[np.ndarray, float]:
             with self._timing.measure("Basler.get_array"):
                 frame = image.GetArray()
 
+            if not self._logged_first_frame:
+                self._logged_first_frame = True
+                LOG.info(
+                    "[Basler] first frame device_id=%s shape=%s dtype=%s nbytes=%.2f MB "
+                    "camera_pixel_format=%s output_format=%s preserve_mono=%s",
+                    self._device_id,
+                    frame.shape,
+                    frame.dtype,
+                    frame.nbytes / (1024 * 1024),
+                    self._camera_pixel_format,
+                    self.actual_output_format,
+                    self._preserve_mono,
+                )
+
             with self._timing.measure("Basler.release"):
                 grab_result.Release()
                 grab_result = None

diff --git a/dlclivegui/cameras/backends/gentl_backend.py b/dlclivegui/cameras/backends/gentl_backend.py
@@ -99,6 +99,9 @@ def __init__(self, settings):
 
         self._pixel_format: str = ns.get("pixel_format") or props.get("pixel_format", "auto")
         self._pixel_format = str(self._pixel_format).strip()
+        self._camera_pixel_format: str | None = None
+        self._actual_output_format: str | None = None
+
         self._rotate: int = int(ns.get("rotate", props.get("rotate", 0))) % 360
         self._crop: tuple[int, int, int, int] | None = self._parse_crop(ns.get("crop", props.get("crop")))
 
@@ -169,6 +172,16 @@ def actual_exposure(self) -> float | None:
     def actual_gain(self) -> float | None:
         return self._actual_gain
 
+    @property
+    def actual_pixel_format(self) -> str | None:
+        """Camera/native pixel format selected on the GenICam PixelFormat node."""
+        return self._camera_pixel_format or (self._pixel_format if self._pixel_format != "auto" else None)
+
+    @property
+    def actual_output_format(self) -> str | None:
+        """Current GenTL backend emits OpenCV-native BGR uint8 frames."""
+        return self._actual_output_format or "BGR8"
+
     @classmethod
     def is_available(cls) -> bool:
         return Harvester is not None
@@ -593,6 +606,21 @@ def waits_for_hardware_trigger(self) -> bool:
         role = str(self._trigger_attr(getattr(self, "_trigger", None), "role", "off") or "off").lower()
         return role in {"external", "follower"}
 
+    @staticmethod
+    def _output_format_for_frame(frame: np.ndarray) -> str:
+        if frame.ndim == 2:
+            if frame.dtype == np.uint8:
+                return "Mono8"
+            return f"Mono{frame.dtype}"
+        if frame.ndim == 3:
+            channels = frame.shape[2]
+            if channels == 3 and frame.dtype == np.uint8:
+                return "BGR8"
+            if channels == 4 and frame.dtype == np.uint8:
+                return "BGRA8"
+            return f"{channels}ch-{frame.dtype}"
+        return str(frame.dtype)
+
     def read(self) -> tuple[np.ndarray, float]:
         if self._acquirer is None:
             raise RuntimeError("GenTL image acquirer not initialised")
@@ -631,6 +659,7 @@ def read(self) -> tuple[np.ndarray, float]:
                 self._read_telemetry(self._acquirer.remote_device.node_map)
             except Exception:
                 pass
+        self._actual_output_format = self._output_format_for_frame(frame)
 
         return frame, timestamp
 
@@ -1340,11 +1369,14 @@ def _configure_pixel_format(self, node_map) -> None:
 
             pixel_format_node.value = selected
             self._pixel_format = str(pixel_format_node.value)
+            self._camera_pixel_format = self._pixel_format
 
             LOG.debug("GenTL pixel format selected: %s", self._pixel_format)
 
         except Exception as e:
             LOG.warning("Failed to configure pixel format '%s': %s", self._pixel_format, e)
+            if self._pixel_format and self._pixel_format.lower() != "auto":
+                self._camera_pixel_format = self._pixel_format
 
     def _configure_trigger(self, node_map) -> None:
         cfg = self._trigger
@@ -1811,7 +1843,13 @@ def _read_telemetry(self, node_map) -> None:
 
             pixel_format = self._node_str(node_map, "PixelFormat")
             if pixel_format is not None:
+                self._camera_pixel_format = pixel_format
                 ns["actual_pixel_format"] = pixel_format
+                ns["detected_pixel_format"] = pixel_format
+
+            output_format = self.actual_output_format
+            if output_format is not None:
+                ns["actual_output_format"] = output_format
 
         except Exception:
             pass

diff --git a/dlclivegui/cameras/backends/opencv_backend.py b/dlclivegui/cameras/backends/opencv_backend.py
@@ -254,6 +254,16 @@ def actual_gain(self) -> None:
         """Not supported by OpenCV backend."""
         return None
 
+    @property
+    def actual_pixel_format(self) -> str | None:
+        """OpenCV does not reliably expose native camera pixel format."""
+        return None
+
+    @property
+    def actual_output_format(self) -> str | None:
+        """OpenCV VideoCapture returns BGR frames in this backend."""
+        return "BGR8"
+
     # ----------------------------
     # Internal helpers
     # ----------------------------

diff --git a/dlclivegui/cameras/base.py b/dlclivegui/cameras/base.py
@@ -68,6 +68,7 @@ class SupportLevel(str, Enum):
     "set_fps": SupportLevel.UNSUPPORTED,
     "set_exposure": SupportLevel.UNSUPPORTED,
     "set_gain": SupportLevel.UNSUPPORTED,
+    "preserve_mono": SupportLevel.UNSUPPORTED,
     "device_discovery": SupportLevel.UNSUPPORTED,
     "stable_identity": SupportLevel.UNSUPPORTED,
     "hardware_trigger": SupportLevel.UNSUPPORTED,
@@ -98,6 +99,14 @@ def static_capabilities(cls) -> dict[str, SupportLevel]:
         """Return a dict describing supported features for UI purposes."""
         return DEFAULT_CAPABILITIES
 
+    @property
+    def actual_pixel_format(self) -> str | None:
+        return None
+
+    @property
+    def recommended_preserve_mono(self) -> bool | None:
+        return None
+
     @classmethod
     def options_key(cls) -> str:
         """Return the key used to store this backend's options in CameraSettings."""