feat(compressors/proposal): add OWLv2 object detection pipeline and typed results

- switch OWLv2 loader return type to Owlv2ForObjectDetection
- add detect_objects and detect_objects_batch with two-stage score filtering
- add DetectionResult typed dict and conversion helper for post-processed outputs
- export new detection APIs from proposal module

mini-nav/compressors/proposal/__init__.py

@@ -1,9 +1,16 @@
-"""Proposal module — SAM mask generation and extraction."""
+"""Proposal module — SAM mask generation and OWLv2 object detection."""
 
-from .core import generate_proposals, generate_proposals_batch
+from .core import (
+    detect_objects,
+    detect_objects_batch,
+    generate_proposals,
+    generate_proposals_batch,
+)
 from .utils import extract_masked_region
 
 __all__ = [
+    "detect_objects",
+    "detect_objects_batch",
     "generate_proposals",
     "generate_proposals_batch",
     "extract_masked_region",

mini-nav/compressors/proposal/core.py

@@ -1,13 +1,25 @@
 """SAM mask proposal generation via bounding box prompts."""
 
-from typing import Any, Sequence
+from typing import Any, Sequence, TypedDict
 
 import numpy as np
+import torch
 from PIL import Image
-from transformers import Sam2Model, Sam2Processor
+from transformers import (
+    Owlv2ForObjectDetection,
+    Owlv2Processor,
+    Sam2Model,
+    Sam2Processor,
+)
 from utils import get_device
 
 
+class DetectionResult(TypedDict):
+    bbox: list[float]
+    score: float
+    label: str
+
+
 def generate_proposals(
     model: Sam2Model,
     processor: Sam2Processor,
@@ -90,6 +102,103 @@ def generate_proposals_batch(
     return [_masks_to_proposals(image_masks) for image_masks in all_masks]
 
 
+def detect_objects(
+    model: Owlv2ForObjectDetection,
+    processor: Owlv2Processor,
+    image: Image.Image,
+    text_labels: list[str],
+    score_threshold: float = 0.25,
+    postprocess_threshold: float = 0.1,
+) -> list[DetectionResult]:
+    """Detect objects in a single image using OWLv2 with text labels.
+
+    Runs OWLv2 object detection on a single image using provided text label
+    queries. Applies post-process thresholding first, then filters by
+    score_threshold.
+
+    Args:
+        model: Owlv2ForObjectDetection instance.
+        processor: Owlv2Processor instance.
+        image: PIL Image to detect objects in.
+        text_labels: List of label groups, e.g., ["cat", "dog"], ["car"].
+        score_threshold: Minimum score for final detection results (>=).
+        postprocess_threshold: Threshold for processor's post-processing (>=).
+
+    Returns:
+        List of DetectionResult dicts with bbox, score, label.
+    """
+    device = get_device()
+    inputs = processor(text=text_labels, images=image, return_tensors="pt").to(device)
+    with torch.no_grad():
+        outputs = model(**inputs)
+    target_sizes = [(image.height, image.width)]
+    result = processor.post_process_grounded_object_detection(
+        outputs=outputs,
+        target_sizes=target_sizes,
+        threshold=postprocess_threshold,
+        text_labels=[text_labels],
+    )[0]
+    return _to_detection_results(result, score_threshold)
+
+
+def detect_objects_batch(
+    model: Owlv2ForObjectDetection,
+    processor: Owlv2Processor,
+    images: Sequence[Image.Image],
+    text_labels_per_image: list[list[str]],
+    score_threshold: float = 0.25,
+    postprocess_threshold: float = 0.1,
+) -> list[list[DetectionResult]]:
+    """Detect objects in a batch of images using OWLv2 with text labels.
+
+    Runs OWLv2 object detection on multiple images using per-image text label
+    queries. Processes all images in a single batch inference call.
+
+    Args:
+        model: Owlv2ForObjectDetection instance.
+        processor: Owlv2Processor instance.
+        images: Sequence of PIL Images to detect objects in.
+        text_labels_per_image: Text labels per image, outer list matches images length.
+            Each inner list is per-image label, e.g., [["cat", "dog"], ["car"]].
+        score_threshold: Minimum score for final detection results (>=).
+        postprocess_threshold: Threshold for processor's post-processing (>=).
+
+    Returns:
+        List of lists of DetectionResult dicts, one inner list per image.
+
+    Raises:
+        ValueError: If len(images) != len(text_labels_per_image).
+    """
+    image_list = list(images)
+    if not image_list:
+        return []
+
+    if len(image_list) != len(text_labels_per_image):
+        raise ValueError(
+            f"Length mismatch: {len(image_list)} images, "
+            f"{len(text_labels_per_image)} text label groups"
+        )
+
+    device = get_device()
+    inputs = processor(
+        text=text_labels_per_image,
+        images=image_list,
+        return_tensors="pt",
+    ).to(device)
+    with torch.no_grad():
+        outputs = model(**inputs)
+
+    target_sizes = [(img.height, img.width) for img in image_list]
+    results = processor.post_process_grounded_object_detection(
+        outputs=outputs,
+        target_sizes=target_sizes,
+        threshold=postprocess_threshold,
+        text_labels=text_labels_per_image,
+    )
+
+    return [_to_detection_results(result, score_threshold) for result in results]
+
+
 def _masks_to_proposals(masks: Any) -> list[dict[str, Any]]:
     """Convert model output masks to list of mask dicts."""
     mask_array = _to_numpy_mask_array(masks)
@@ -152,3 +261,39 @@ def _build_mask_dict(mask_array: np.ndarray) -> dict[str, Any] | None:
         "predicted_iou": None,
         "stability_score": None,
     }
+
+
+def _to_detection_results(
+    result: dict[str, Any], score_threshold: float
+) -> list[DetectionResult]:
+    """Convert OWLv2 post-process result to detection results list.
+
+    Extracts boxes, scores, and text labels from result dict, converts tensors
+    to Python native types, and filters by score threshold.
+
+    Args:
+        result: OWLv2 post-process result dict with keys 'boxes', 'scores',
+            'text_labels'.
+        score_threshold: Minimum score to include detection (>= threshold).
+
+    Returns:
+        List of DetectionResult dicts with bbox, score, label.
+    """
+    boxes = result["boxes"]
+    scores = result["scores"]
+    text_labels = result["text_labels"]
+
+    detections: list[DetectionResult] = []
+    for box, score, label in zip(boxes, scores, text_labels):
+        score_float = float(score.item())
+        if score_float >= score_threshold:
+            bbox = [float(v) for v in box.tolist()]
+            detections.append(
+                {
+                    "bbox": bbox,
+                    "score": score_float,
+                    "label": str(label),
+                }
+            )
+
+    return detections