Add options to set background color when exporting video

docs/guides/cli.md

@@ -389,6 +389,9 @@ optional arguments:
   --distinctly_color DISTINCTLY_COLOR
                         Specify how to color instances. Options include: "instances",
                         "edges", and "nodes" (default: "instances")
+  --background BACKGROUND
+                        Specify the type of background to be used to save the videos.
+                        Options: original, black, white and grey. (default: "original")
 ```
 
 ## Debugging

sleap/config/labeled_clip_form.yaml

@@ -18,6 +18,10 @@ main:
     label: Use GUI Visual Settings (colors, line widths)
     type: bool
     default: true
+  - name: background
+    label: Video Background
+    type: list
+    options: Original,Black,White,Grey
   - name: open_when_done
     label: Open When Done Saving
     type: bool

sleap/gui/commands.py

@@ -1295,6 +1295,7 @@ def do_action(context: CommandContext, params: dict):
             frames=list(params["frames"]),
             fps=params["fps"],
             color_manager=params["color_manager"],
+            background=params["background"],
             show_edges=params["show edges"],
             edge_is_wedge=params["edge_is_wedge"],
             marker_size=params["marker size"],
@@ -1354,6 +1355,7 @@ def ask(context: CommandContext, params: dict) -> bool:
         params["fps"] = export_options["fps"]
         params["scale"] = export_options["scale"]
         params["open_when_done"] = export_options["open_when_done"]
+        params["background"] = export_options["background"]
 
         params["crop"] = None
 

sleap/io/video.py

@@ -1118,8 +1118,9 @@ def get_frames(self, idxs: Union[int, Iterable[int]]) -> np.ndarray:
 
     def get_frames_safely(self, idxs: Iterable[int]) -> Tuple[List[int], np.ndarray]:
         """Return list of frame indices and frames which were successfully loaded.
+        Args:
+            idxs: An iterable object that contains the indices of frames.
 
-        idxs: An iterable object that contains the indices of frames.
 
         Returns: A tuple of (frame indices, frames), where
             * frame indices is a subset of the specified idxs, and

sleap/io/visuals.py

@@ -27,7 +27,13 @@
 _sentinel = object()
 
 
-def reader(out_q: Queue, video: Video, frames: List[int], scale: float = 1.0):
+def reader(
+    out_q: Queue,
+    video: Video,
+    frames: List[int],
+    scale: float = 1.0,
+    background: str = "original",
+):
     """Read frame images from video and send them into queue.
 
     Args:
@@ -36,11 +42,13 @@ def reader(out_q: Queue, video: Video, frames: List[int], scale: float = 1.0):
         video: The `Video` object to read.
         frames: Full list frame indexes we want to read.
         scale: Output scale for frame images.
+        background: output video background. Either Original, Black, White, Grey
 
     Returns:
         None.
     """
 
+    background = background.lower()
     cv2.setNumThreads(usable_cpu_count())
 
     total_count = len(frames)
@@ -64,6 +72,18 @@ def reader(out_q: Queue, video: Video, frames: List[int], scale: float = 1.0):
             loaded_chunk_idxs, video_frame_images = video.get_frames_safely(
                 frames_idx_chunk
             )
+            if background != "original":
+                # fill the frame with the color
+                if background == "black":
+                    fill = 0
+                elif background == "grey":
+                    fill = 127
+                elif background == "white":
+                    # background == White
+                    fill = 255
+                else:
+                    raise ValueError(f"Invalid background color: {background}")
+                video_frame_images = video_frame_images * 0 + fill
 
             if not loaded_chunk_idxs:
                 print(f"No frames could be loaded from chunk {chunk_i}")
@@ -497,6 +517,7 @@ def save_labeled_video(
     fps: int = 15,
     scale: float = 1.0,
     crop_size_xy: Optional[Tuple[int, int]] = None,
+    background: str = "original",
     show_edges: bool = True,
     edge_is_wedge: bool = False,
     marker_size: int = 4,
@@ -515,6 +536,7 @@ def save_labeled_video(
         fps: Frames per second for output video.
         scale: scale of image (so we can scale point locations to match)
         crop_size_xy: size of crop around instances, or None for full images
+        background: output video background. Either Original, Black, White, Grey
         show_edges: whether to draw lines between nodes
         edge_is_wedge: whether to draw edges as wedges (draw as line if False)
         marker_size: Size of marker in pixels before scaling by `scale`
@@ -537,7 +559,7 @@ def save_labeled_video(
     q2 = Queue(maxsize=10)
     progress_queue = Queue()
 
-    thread_read = Thread(target=reader, args=(q1, video, frames, scale))
+    thread_read = Thread(target=reader, args=(q1, video, frames, scale, background))
     thread_mark = VideoMarkerThread(
         in_q=q1,
         out_q=q2,
@@ -695,6 +717,15 @@ def main(args: list = None):
             "and 'nodes' (default: 'nodes')"
         ),
     )
+    parser.add_argument(
+        "--background",
+        type=str,
+        default="original",
+        help=(
+            "Specify the type of background to be used to save the videos."
+            "Options for background: original, black, white and grey"
+        ),
+    )
     args = parser.parse_args(args=args)
     labels = Labels.load_file(
         args.data_path, video_search=[os.path.dirname(args.data_path)]
@@ -730,6 +761,7 @@ def main(args: list = None):
         marker_size=args.marker_size,
         palette=args.palette,
         distinctly_color=args.distinctly_color,
+        background=args.background,
     )
 
     print(f"Video saved as: {filename}")

tests/io/test_visuals.py

@@ -63,6 +63,16 @@ def test_serial_pipeline(centered_pair_predictions, tmpdir):
     )
 
 
+@pytest.mark.parametrize("background", ["original", "black", "white", "grey"])
+def test_sleap_render_with_different_backgrounds(background):
+    args = (
+        f"-o test_{background}.avi -f 2 --scale 1.2 --frames 1,2 --video-index 0 --background {background} "
+        "tests/data/json_format_v2/centered_pair_predictions.json".split()
+    )
+    sleap_render(args)
+    assert os.path.exists(f"test_{background}.avi")
+
+
 def test_sleap_render(centered_pair_predictions):
     args = (
         "-o testvis.avi -f 2 --scale 1.2 --frames 1,2 --video-index 0 "