Add support for HDR on the Camera Module 3

.vscode/settings.json

@@ -50,6 +50,9 @@
         "randr",
         "raspberrypi",
         "rclone",
+        "subdev",
+        "subdevice",
+        "subdevices",
         "Tailscale",
         "tflite",
         "Twidec",

README.adoc

@@ -198,6 +198,41 @@ ln --force --relative --symbolic systemd/user/* ~/.config/systemd/user/
 systemctl --user enable --now detectionator.service
 ----
 
+== HDR
+
+The Raspberry Pi Camera Module 3 supports HDR, but only at a lower resolution.
+HDR support has to toggled when `detectionator.py` isn't running and requires passing a special flag to `detectionator.py`.
+
+. Show the available V4L subdevices.
++
+[,sh]
+----
+ls /dev/v4l-subdev*
+/dev/v4l-subdev0  /dev/v4l-subdev1  /dev/v4l-subdev2  /dev/v4l-subdev3
+----
+
+. To enable HDR support for the Raspberry Pi Camera Module 3, use the following command on one of the V4L subdevices.
+In my case, this ended up being `/dev/v4l-subdev2`.
++
+[,sh]
+----
+v4l2-ctl --set-ctrl wide_dynamic_range=1 --device /dev/v4l-subdev2
+----
+
+. Now that the Camera Module 3 is configured, just run `detectionator.py` with the `--hdr` flag to default to the proper resolution sizes when HDR is enabled.
++
+[,sh]
+----
+./detectionator.py --hdr
+----
+
+. To disable HDR support for the Raspberry Pi Camera Module 3, use this command with the corresponding V4L subdevice.
++
+[,sh]
+----
+v4l2-ctl --set-ctrl wide_dynamic_range=0 --device /dev/v4l-subdev2
+----
+
 == Development
 
 It's recommended to use the provided {pre-commit} checks when developing.

detectionator.py

@@ -21,23 +21,14 @@
 
 
 # todo Figure out the best values for the normal and low resolution sizes.
-# normal_size = (640, 480)
-# low_resolution_size = (320, 240)
-
 # Camera Module 3:
 #   HDR disabled: 4608 x 2592
 #   HDR enabled: 2304 x 1296
 #
-# Enable:
-#   v4l2-ctl --set-ctrl wide_dynamic_range=1 -d /dev/v4l-subdev2
-#
-# Disable:
-#   v4l2-ctl --set-ctrl wide_dynamic_range=0 -d /dev/v4l-subdev2
-#
-normal_size = (4608, 2592)
-# low_resolution_size = (576, 324)
-# low_resolution_size = (1152, 648)
+default_normal_resolution_size = (4608, 2592)
 default_low_resolution_size = (2304, 1296)
+default_normal_resolution_size_hdr = (2304, 1296)
+default_low_resolution_size_hdr = (1152, 648)
 
 
 def ReadLabelFile(file_path):
@@ -99,16 +90,27 @@ def main():
         help="The device path for the GPS serial device.",
         default="/dev/ttyUSBAdafruitUltimateGps",
     )
+    parser.add_argument(
+        "--hdr",
+        action=argparse.BooleanOptionalAction,
+        help="This option uses the default resolution for the Camera Module 3 when in HDR mode.",
+    )
     parser.add_argument("--label", help="Path of the labels file.")
     parser.add_argument(
         "--low-resolution-width",
         help="The width to use for the low resolution size.",
-        default=default_low_resolution_size[0],
     )
     parser.add_argument(
         "--low-resolution-height",
         help="The height to use for the low resolution size.",
-        default=default_low_resolution_size[1],
+    )
+    parser.add_argument(
+        "--normal-resolution-width",
+        help="The width to use for the normal resolution size.",
+    )
+    parser.add_argument(
+        "--normal-resolution-height",
+        help="The height to use for the normal resolution size.",
     )
     parser.add_argument(
         "--match", help="The labels for which to capture photographs", nargs="*"
@@ -136,12 +138,32 @@ def main():
     if label_file:
         labels = ReadLabelFile(label_file)
 
+    normal_resolution_size = default_normal_resolution_size
+    low_resolution_size = default_low_resolution_size
+    if args.hdr:
+        normal_resolution_size = default_normal_resolution_size_hdr
+        low_resolution_size = default_low_resolution_size_hdr
+    normal_resolution_width = normal_resolution_size[0]
+    normal_resolution_height = normal_resolution_size[1]
+    low_resolution_width = low_resolution_size[0]
+    low_resolution_height = low_resolution_size[1]
+
+    if args.normal_resolution_width:
+        normal_resolution_width = args.normal_resolution_width
+    if args.normal_resolution_height:
+        normal_resolution_height = args.normal_resolution_height
+
+    if args.low_resolution_width:
+        low_resolution_width = args.low_resolution_width
+    if args.low_resolution_height:
+        low_resolution_height = args.low_resolution_height
+
     if (
-        normal_size[0] / args.low_resolution_width
-        != normal_size[1] / args.low_resolution_height
+        normal_resolution_width / low_resolution_width
+        != normal_resolution_height / low_resolution_height
     ):
         print(
-            f"The low resolution width, '{args.low_resolution_width}', and low resolution height, '{args.low_resolution_height}' must be a fraction of the normal size, '{normal_size[0]}x{normal_size[1]}'"
+            f"The low resolution width, '{low_resolution_width}', and low resolution height, '{low_resolution_height}' must be a fraction of the normal size, '{normal_resolution_width}x{normal_resolution_height}'"
         )
         sys.exit(1)
 
@@ -175,12 +197,12 @@ def main():
         picam2.options["quality"] = 95
         picam2.options["compress_level"] = 9
         config = picam2.create_still_configuration(
-            main={"size": normal_size},
+            main={"size": (normal_resolution_width, normal_resolution_height)},
             lores={
                 # Only Pi 5 and newer can use formats besides YUV here.
                 # This avoids having to convert the image format for OpenCV later.
                 "format": "RGB888",
-                "size": (args.low_resolution_width, args.low_resolution_height),
+                "size": (low_resolution_width, low_resolution_height),
             },
             buffer_count=4,
             # Don't display anything in the preview window since the system is running headless.