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311 lines
10 KiB
Python
311 lines
10 KiB
Python
"""Image synthesizer for generating synthetic object detection datasets."""
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import random
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from pathlib import Path
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import numpy as np
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from PIL import Image
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from PIL.Image import Resampling
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class ImageSynthesizer:
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"""Synthesizes composite images from background and object images with masks."""
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def __init__(
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self,
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dataset_root: Path,
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output_dir: Path,
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num_objects_range: tuple[int, int] = (3, 8),
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num_scenes: int = 1000,
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object_scale_range: tuple[float, float] = (0.1, 0.4),
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rotation_range: tuple[int, int] = (-30, 30),
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overlap_threshold: float = 0.3,
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seed: int = 42,
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):
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"""
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Initialize the image synthesizer.
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Args:
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dataset_root: Root directory of the dataset (InsDet-FULL)
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output_dir: Directory to save synthesized images
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num_objects_range: Range of number of objects per scene
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num_scenes: Number of scenes to generate
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object_scale_range: Range of object scale relative to background
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rotation_range: Range of rotation angles in degrees
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overlap_threshold: Maximum allowed overlap ratio
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seed: Random seed for reproducibility
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"""
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self.dataset_root = Path(dataset_root)
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self.output_dir = Path(output_dir)
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self.num_objects_range = num_objects_range
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self.num_scenes = num_scenes
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self.object_scale_range = object_scale_range
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self.rotation_range = rotation_range
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self.overlap_threshold = overlap_threshold
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self.seed = seed
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self.background_dir = self.dataset_root / "Background"
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self.objects_dir = self.dataset_root / "Objects"
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self.scenes_dir = self.dataset_root / "Scenes"
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# Will be populated on first use
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self._background_categories: list[str] | None = None
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self._object_categories: list[str] | None = None
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@property
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def background_images(self) -> list[Path]:
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"""List of background image paths."""
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if self._background_categories is None:
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self._background_categories = sorted(
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[
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p.name
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for p in self.background_dir.iterdir()
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if p.suffix in [".jpg", ".jpeg", ".png"]
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]
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)
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# Return as list of Path for type compatibility
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return [self.background_dir / name for name in self._background_categories] # type: ignore[return-value]
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@property
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def object_categories(self) -> list[str]:
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"""List of object categories."""
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if self._object_categories is None:
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self._object_categories = sorted(
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[d.name for d in self.objects_dir.iterdir() if d.is_dir()]
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)
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return self._object_categories
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def load_background(self, path: Path) -> Image.Image:
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"""Load a background image.
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Args:
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path: Background image path
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Returns:
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PIL Image
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"""
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return Image.open(path).convert("RGB")
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def load_object(self, category: str, angle: int) -> tuple[Image.Image, Image.Image]:
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"""Load an object image and its mask.
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Args:
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category: Object category name (e.g., '099_mug_blue')
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angle: Angle index (1-24)
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Returns:
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Tuple of (image, mask) as PIL Images
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"""
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img_path = self.objects_dir / category / "images" / f"{angle:03d}.jpg"
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mask_path = self.objects_dir / category / "masks" / f"{angle:03d}.png"
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image = Image.open(img_path).convert("RGB")
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mask = Image.open(mask_path).convert("L")
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return image, mask
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def get_random_background(self) -> tuple[Image.Image, Path]:
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"""Get a random background image.
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Returns:
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Tuple of (image, path)
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"""
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path = random.choice(self.background_images)
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return self.load_background(path), path
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def get_random_object(self) -> tuple[Image.Image, Image.Image, str]:
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"""Get a random object with its mask.
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Returns:
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Tuple of (image, mask, category_name)
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"""
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category = random.choice(self.object_categories)
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angle = random.randint(1, 24)
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image, mask = self.load_object(category, angle)
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return image, mask, category
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def _rotate_image_and_mask(
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self, image: Image.Image, mask: Image.Image, angle: float
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) -> tuple[Image.Image, Image.Image]:
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"""Rotate image and mask together."""
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image = image.rotate(angle, resample=Resampling.BILINEAR, expand=True)
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mask = mask.rotate(angle, resample=Resampling.BILINEAR, expand=True)
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return image, mask
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def _compute_overlap(
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self, box1: tuple[int, int, int, int], box2: tuple[int, int, int, int]
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) -> float:
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"""Compute overlap ratio between two boxes.
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Args:
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box1: (xmin, ymin, xmax, ymax)
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box2: (xmin, ymin, xmax, ymax)
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Returns:
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Overlap ratio (area of intersection / area of smaller box)
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"""
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x1_min, y1_min, x1_max, y1_max = box1
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x2_min, y2_min, x2_max, y2_max = box2
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# Compute intersection
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inter_xmin = max(x1_min, x2_min)
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inter_ymin = max(y1_min, y2_min)
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inter_xmax = min(x1_max, x2_max)
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inter_ymax = min(y1_max, y2_max)
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if inter_xmax <= inter_xmin or inter_ymax <= inter_ymin:
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return 0.0
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inter_area = (inter_xmax - inter_xmin) * (inter_ymax - inter_ymin)
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box1_area = (x1_max - x1_min) * (y1_max - y1_min)
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box2_area = (x2_max - x2_min) * (y2_max - y2_min)
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min_area = min(box1_area, box2_area)
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return inter_area / (min_area if min_area > 0 else 0.0)
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def _has_overlap(
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self,
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new_box: tuple[int, int, int, int],
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existing_boxes: list[tuple[int, int, int, int]],
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) -> bool:
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"""Check if new_box overlaps with any existing boxes.
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Args:
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new_box: The new bounding box (xmin, ymin, xmax, ymax)
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existing_boxes: List of existing bounding boxes
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Returns:
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True if any overlap exceeds threshold, False otherwise
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"""
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for existing_box in existing_boxes:
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if self._compute_overlap(new_box, existing_box) > self.overlap_threshold:
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return True
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return False
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def _place_object(
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self,
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background: Image.Image,
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obj_image: Image.Image,
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obj_mask: Image.Image,
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existing_boxes: list[tuple[int, int, int, int]],
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scale: float,
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) -> tuple[Image.Image, Image.Image, tuple[int, int, int, int]] | None:
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"""Place an object on the background without exceeding overlap threshold.
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Args:
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background: Background PIL Image
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obj_image: Object PIL Image (RGB)
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obj_mask: Object PIL Image (L)
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existing_boxes: List of existing object boxes
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scale: Scale factor for the object
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Returns:
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Tuple of (new_background, updated_mask, new_box) or None if placement failed
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"""
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bg_w, bg_h = background.size
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# Scale object
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obj_w, obj_h = obj_image.size
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new_w = int(obj_w * scale)
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new_h = int(obj_h * scale)
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if new_w <= 0 or new_h <= 0 or new_w > bg_w or new_h > bg_h:
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return None
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obj_image = obj_image.resize((new_w, new_h), Resampling.LANCZOS)
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obj_mask = obj_mask.resize((new_w, new_h), Resampling.LANCZOS)
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# Try to find a valid position
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max_attempts = 50
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for _ in range(max_attempts):
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# Random position
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x = random.randint(0, bg_w - new_w)
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y = random.randint(0, bg_h - new_h)
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new_box = (x, y, x + new_w, y + new_h)
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# Check overlap with existing boxes
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if not self._has_overlap(new_box, existing_boxes):
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# Composite object onto background using Pillow's paste method
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background = background.copy()
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background.paste(obj_image, (x, y), mask=obj_mask)
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return background, obj_mask, new_box
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return None
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def synthesize_scene(
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self,
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) -> tuple[Image.Image, list[tuple[str, int, int, int, int]]]:
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"""Synthesize a single scene with random objects.
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Returns:
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Tuple of (synthesized_image, list of (category, xmin, ymin, xmax, ymax))
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"""
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random.seed(self.seed)
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np.random.seed(self.seed)
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# Load background
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background, _ = self.get_random_background()
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# Determine number of objects
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num_objects = random.randint(*self.num_objects_range)
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# Place objects
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placed_boxes: list[tuple[int, int, int, int]] = []
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annotations: list[tuple[str, int, int, int, int]] = []
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for _ in range(num_objects):
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# Get random object
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obj_image, obj_mask, obj_category = self.get_random_object()
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# Get random scale
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scale = random.uniform(*self.object_scale_range)
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# Get random rotation
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angle = random.uniform(*self.rotation_range)
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obj_image, obj_mask = self._rotate_image_and_mask(
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obj_image, obj_mask, angle
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)
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# Try to place object
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result = self._place_object(
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background, obj_image, obj_mask, placed_boxes, scale
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)
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if result is not None:
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background, _, box = result
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placed_boxes.append(box)
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annotations.append((obj_category, box[0], box[1], box[2], box[3]))
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return background, annotations
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def generate(self) -> list[Path]:
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"""Generate all synthesized scenes.
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Returns:
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List of paths to generated images
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"""
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self.output_dir.mkdir(parents=True, exist_ok=True)
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generated_files: list[Path] = []
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for i in range(self.num_scenes):
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# Update seed for each scene
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random.seed(self.seed + i)
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np.random.seed(self.seed + i)
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image, annotations = self.synthesize_scene()
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# Save image
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img_path = self.output_dir / f"synth_{i:04d}.jpg"
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image.save(img_path, quality=95)
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# Save annotation
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anno_path = self.output_dir / f"synth_{i:04d}.txt"
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with open(anno_path, "w", encoding="utf-8") as f:
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for category, xmin, ymin, xmax, ymax in annotations:
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f.write(f"{category} {xmin} {ymin} {xmax} {ymax}\n")
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generated_files.append(img_path)
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return generated_files
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