Small fix

Reviewed-on: #2

config/app_config.yaml

@@ -12,12 +12,26 @@ image_repository:
 models:
   default_base_model: yolov8s-seg.pt
   models_directory: data/models
+  base_model_choices:
+  - yolov8s-seg.pt
+  - yolo11s-seg.pt
 training:
   default_epochs: 100
   default_batch_size: 16
-  default_imgsz: 640
+  default_imgsz: 1024
   default_patience: 50
   default_lr0: 0.01
+  two_stage:
+    enabled: false
+    stage1:
+      epochs: 20
+      lr0: 0.0005
+      patience: 10
+      freeze: 10
+    stage2:
+      epochs: 150
+      lr0: 0.0003
+      patience: 30
   last_dataset_yaml: /home/martin/code/object_detection/data/datasets/data.yaml
   last_dataset_dir: /home/martin/code/object_detection/data/datasets
 detection:

src/database/db_manager.py

@@ -13,8 +13,9 @@ import hashlib
 import yaml
 
 from src.utils.logger import get_logger
+from src.utils.image import Image
 
-IMAGE_EXTENSIONS = (".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp")
+IMAGE_EXTENSIONS = tuple(Image.SUPPORTED_EXTENSIONS)
 
 logger = get_logger(__name__)
 
@@ -450,6 +451,25 @@ class DatabaseManager:
             filters["model_id"] = model_id
         return self.get_detections(filters)
 
+    def delete_detections_for_image(
+        self, image_id: int, model_id: Optional[int] = None
+    ) -> int:
+        """Delete detections tied to a specific image and optional model."""
+        conn = self.get_connection()
+        try:
+            cursor = conn.cursor()
+            if model_id is not None:
+                cursor.execute(
+                    "DELETE FROM detections WHERE image_id = ? AND model_id = ?",
+                    (image_id, model_id),
+                )
+            else:
+                cursor.execute("DELETE FROM detections WHERE image_id = ?", (image_id,))
+            conn.commit()
+            return cursor.rowcount
+        finally:
+            conn.close()
+
     def delete_detections_for_model(self, model_id: int) -> int:
         """Delete all detections for a specific model."""
         conn = self.get_connection()

src/gui/tabs/annotation_tab.py

@@ -168,7 +168,7 @@ class AnnotationTab(QWidget):
             self,
             "Select Image",
             start_dir,
-            "Images (*.jpg *.jpeg *.png *.tif *.tiff *.bmp)",
+            "Images (*" + " *".join(Image.SUPPORTED_EXTENSIONS) + ")",
         )
 
         if not file_path:

src/gui/tabs/detection_tab.py

@@ -20,12 +20,14 @@ from PySide6.QtWidgets import (
 )
 from PySide6.QtCore import Qt, QThread, Signal
 from pathlib import Path
+from typing import Optional
 
 from src.database.db_manager import DatabaseManager
 from src.utils.config_manager import ConfigManager
 from src.utils.logger import get_logger
 from src.utils.file_utils import get_image_files
 from src.model.inference import InferenceEngine
+from src.utils.image import Image
 
 
 logger = get_logger(__name__)
@@ -147,30 +149,66 @@ class DetectionTab(QWidget):
         self.model_combo.currentIndexChanged.connect(self._on_model_changed)
 
     def _load_models(self):
-        """Load available models from database."""
+        """Load available models from database and local storage."""
         try:
-            models = self.db_manager.get_models()
             self.model_combo.clear()
+            models = self.db_manager.get_models()
+            has_models = False
 
-            if not models:
-                self.model_combo.addItem("No models available", None)
-                self._set_buttons_enabled(False)
-                return
+            known_paths = set()
 
-            # Add base model option
+            # Add base model option first (always available)
             base_model = self.config_manager.get(
                 "models.default_base_model", "yolov8s-seg.pt"
             )
-            self.model_combo.addItem(
-                f"Base Model ({base_model})", {"id": 0, "path": base_model}
-            )
+            if base_model:
+                base_data = {
+                    "id": 0,
+                    "path": base_model,
+                    "model_name": Path(base_model).stem or "Base Model",
+                    "model_version": "pretrained",
+                    "base_model": base_model,
+                    "source": "base",
+                }
+                self.model_combo.addItem(f"Base Model ({base_model})", base_data)
+                known_paths.add(self._normalize_model_path(base_model))
+                has_models = True
 
-            # Add trained models
+            # Add trained models from database
             for model in models:
                 display_name = f"{model['model_name']} v{model['model_version']}"
-                self.model_combo.addItem(display_name, model)
+                model_data = {**model, "path": model.get("model_path")}
+                normalized = self._normalize_model_path(model_data.get("path"))
+                if normalized:
+                    known_paths.add(normalized)
+                self.model_combo.addItem(display_name, model_data)
+                has_models = True
 
-            self._set_buttons_enabled(True)
+            # Discover local model files not yet in the database
+            local_models = self._discover_local_models()
+            for model_path in local_models:
+                normalized = self._normalize_model_path(model_path)
+                if normalized in known_paths:
+                    continue
+
+                display_name = f"Local Model ({Path(model_path).stem})"
+                model_data = {
+                    "id": None,
+                    "path": str(model_path),
+                    "model_name": Path(model_path).stem,
+                    "model_version": "local",
+                    "base_model": Path(model_path).stem,
+                    "source": "local",
+                }
+                self.model_combo.addItem(display_name, model_data)
+                known_paths.add(normalized)
+                has_models = True
+
+            if not has_models:
+                self.model_combo.addItem("No models available", None)
+                self._set_buttons_enabled(False)
+            else:
+                self._set_buttons_enabled(True)
 
         except Exception as e:
             logger.error(f"Error loading models: {e}")
@@ -199,7 +237,7 @@ class DetectionTab(QWidget):
             self,
             "Select Image",
             start_dir,
-            "Images (*.jpg *.jpeg *.png *.tif *.tiff *.bmp)",
+            "Images (*" + " *".join(Image.SUPPORTED_EXTENSIONS) + ")",
         )
 
         if not file_path:
@@ -249,25 +287,39 @@ class DetectionTab(QWidget):
                 QMessageBox.warning(self, "No Model", "Please select a model first.")
                 return
 
-            model_path = model_data["path"]
-            model_id = model_data["id"]
+            model_path = model_data.get("path")
+            if not model_path:
+                QMessageBox.warning(
+                    self, "Invalid Model", "Selected model is missing a file path."
+                )
+                return
 
-            # Ensure we have a valid model ID (create entry for base model if needed)
-            if model_id == 0:
-                # Create database entry for base model
-                base_model = self.config_manager.get(
-                    "models.default_base_model", "yolov8s-seg.pt"
-                )
-                model_id = self.db_manager.add_model(
-                    model_name="Base Model",
-                    model_version="pretrained",
-                    model_path=base_model,
-                    base_model=base_model,
+            if not Path(model_path).exists():
+                QMessageBox.critical(
+                    self,
+                    "Model Not Found",
+                    f"The selected model file could not be found:\n{model_path}",
                 )
+                return
+
+            model_id = model_data.get("id")
+
+            # Ensure we have a database entry for the selected model
+            if model_id in (None, 0):
+                model_id = self._ensure_model_record(model_data)
+                if not model_id:
+                    QMessageBox.critical(
+                        self,
+                        "Model Registration Failed",
+                        "Unable to register the selected model in the database.",
+                    )
+                    return
+
+            normalized_model_path = self._normalize_model_path(model_path) or model_path
 
             # Create inference engine
             self.inference_engine = InferenceEngine(
-                model_path, self.db_manager, model_id
+                normalized_model_path, self.db_manager, model_id
             )
 
             # Get confidence threshold
@@ -338,6 +390,76 @@ class DetectionTab(QWidget):
         self.batch_btn.setEnabled(enabled)
         self.model_combo.setEnabled(enabled)
 
+    def _discover_local_models(self) -> list:
+        """Scan the models directory for standalone .pt files."""
+        models_dir = self.config_manager.get_models_directory()
+        if not models_dir:
+            return []
+
+        models_path = Path(models_dir)
+        if not models_path.exists():
+            return []
+
+        try:
+            return sorted(
+                [p for p in models_path.rglob("*.pt") if p.is_file()],
+                key=lambda p: str(p).lower(),
+            )
+        except Exception as e:
+            logger.warning(f"Error discovering local models: {e}")
+            return []
+
+    def _normalize_model_path(self, path_value) -> str:
+        """Return a normalized absolute path string for comparison."""
+        if not path_value:
+            return ""
+        try:
+            return str(Path(path_value).resolve())
+        except Exception:
+            return str(path_value)
+
+    def _ensure_model_record(self, model_data: dict) -> Optional[int]:
+        """Ensure a database record exists for the selected model."""
+        model_path = model_data.get("path")
+        if not model_path:
+            return None
+
+        normalized_target = self._normalize_model_path(model_path)
+
+        try:
+            existing_models = self.db_manager.get_models()
+            for model in existing_models:
+                existing_path = model.get("model_path")
+                if not existing_path:
+                    continue
+                normalized_existing = self._normalize_model_path(existing_path)
+                if (
+                    normalized_existing == normalized_target
+                    or existing_path == model_path
+                ):
+                    return model["id"]
+
+            model_name = (
+                model_data.get("model_name") or Path(model_path).stem or "Custom Model"
+            )
+            model_version = (
+                model_data.get("model_version") or model_data.get("source") or "local"
+            )
+            base_model = model_data.get(
+                "base_model",
+                self.config_manager.get("models.default_base_model", "yolov8s-seg.pt"),
+            )
+
+            return self.db_manager.add_model(
+                model_name=model_name,
+                model_version=model_version,
+                model_path=normalized_target,
+                base_model=base_model,
+            )
+        except Exception as e:
+            logger.error(f"Failed to ensure model record for {model_path}: {e}")
+            return None
+
     def refresh(self):
         """Refresh the tab."""
         self._load_models()

src/gui/tabs/results_tab.py

@@ -1,15 +1,39 @@
 """
-Results tab for the microscopy object detection application.
+Results tab for browsing stored detections and visualizing overlays.
 """
 
-from PySide6.QtWidgets import QWidget, QVBoxLayout, QLabel, QGroupBox
+from pathlib import Path
+from typing import Dict, List, Optional
+
+from PySide6.QtWidgets import (
+    QWidget,
+    QVBoxLayout,
+    QHBoxLayout,
+    QLabel,
+    QGroupBox,
+    QPushButton,
+    QSplitter,
+    QTableWidget,
+    QTableWidgetItem,
+    QHeaderView,
+    QAbstractItemView,
+    QMessageBox,
+    QCheckBox,
+)
+from PySide6.QtCore import Qt
 
 from src.database.db_manager import DatabaseManager
 from src.utils.config_manager import ConfigManager
+from src.utils.logger import get_logger
+from src.utils.image import Image, ImageLoadError
+from src.gui.widgets import AnnotationCanvasWidget
+
+
+logger = get_logger(__name__)
 
 
 class ResultsTab(QWidget):
-    """Results tab placeholder."""
+    """Results tab showing detection history and preview overlays."""
 
     def __init__(
         self, db_manager: DatabaseManager, config_manager: ConfigManager, parent=None
@@ -18,29 +42,398 @@ class ResultsTab(QWidget):
         self.db_manager = db_manager
         self.config_manager = config_manager
 
+        self.detection_summary: List[Dict] = []
+        self.current_selection: Optional[Dict] = None
+        self.current_image: Optional[Image] = None
+        self.current_detections: List[Dict] = []
+        self._image_path_cache: Dict[str, str] = {}
+
         self._setup_ui()
+        self.refresh()
 
     def _setup_ui(self):
         """Setup user interface."""
         layout = QVBoxLayout()
 
-        group = QGroupBox("Results")
-        group_layout = QVBoxLayout()
-        label = QLabel(
-            "Results viewer will be implemented here.\n\n"
-            "Features:\n"
-            "- Detection history browser\n"
-            "- Advanced filtering\n"
-            "- Statistics dashboard\n"
-            "- Export functionality"
-        )
-        group_layout.addWidget(label)
-        group.setLayout(group_layout)
+        # Splitter for list + preview
+        splitter = QSplitter(Qt.Horizontal)
 
-        layout.addWidget(group)
-        layout.addStretch()
+        # Left pane: detection list
+        left_container = QWidget()
+        left_layout = QVBoxLayout()
+        left_layout.setContentsMargins(0, 0, 0, 0)
+
+        controls_layout = QHBoxLayout()
+        self.refresh_btn = QPushButton("Refresh")
+        self.refresh_btn.clicked.connect(self.refresh)
+        controls_layout.addWidget(self.refresh_btn)
+        controls_layout.addStretch()
+        left_layout.addLayout(controls_layout)
+
+        self.results_table = QTableWidget(0, 5)
+        self.results_table.setHorizontalHeaderLabels(
+            ["Image", "Model", "Detections", "Classes", "Last Updated"]
+        )
+        self.results_table.horizontalHeader().setSectionResizeMode(
+            0, QHeaderView.Stretch
+        )
+        self.results_table.horizontalHeader().setSectionResizeMode(
+            1, QHeaderView.Stretch
+        )
+        self.results_table.horizontalHeader().setSectionResizeMode(
+            2, QHeaderView.ResizeToContents
+        )
+        self.results_table.horizontalHeader().setSectionResizeMode(
+            3, QHeaderView.Stretch
+        )
+        self.results_table.horizontalHeader().setSectionResizeMode(
+            4, QHeaderView.ResizeToContents
+        )
+        self.results_table.setSelectionBehavior(QAbstractItemView.SelectRows)
+        self.results_table.setSelectionMode(QAbstractItemView.SingleSelection)
+        self.results_table.setEditTriggers(QAbstractItemView.NoEditTriggers)
+        self.results_table.itemSelectionChanged.connect(self._on_result_selected)
+
+        left_layout.addWidget(self.results_table)
+        left_container.setLayout(left_layout)
+
+        # Right pane: preview canvas and controls
+        right_container = QWidget()
+        right_layout = QVBoxLayout()
+        right_layout.setContentsMargins(0, 0, 0, 0)
+
+        preview_group = QGroupBox("Detection Preview")
+        preview_layout = QVBoxLayout()
+
+        self.preview_canvas = AnnotationCanvasWidget()
+        self.preview_canvas.set_polyline_enabled(False)
+        self.preview_canvas.set_show_bboxes(True)
+        preview_layout.addWidget(self.preview_canvas)
+
+        toggles_layout = QHBoxLayout()
+        self.show_masks_checkbox = QCheckBox("Show Masks")
+        self.show_masks_checkbox.setChecked(False)
+        self.show_masks_checkbox.stateChanged.connect(self._apply_detection_overlays)
+        self.show_bboxes_checkbox = QCheckBox("Show Bounding Boxes")
+        self.show_bboxes_checkbox.setChecked(True)
+        self.show_bboxes_checkbox.stateChanged.connect(self._toggle_bboxes)
+        self.show_confidence_checkbox = QCheckBox("Show Confidence")
+        self.show_confidence_checkbox.setChecked(False)
+        self.show_confidence_checkbox.stateChanged.connect(
+            self._apply_detection_overlays
+        )
+        toggles_layout.addWidget(self.show_masks_checkbox)
+        toggles_layout.addWidget(self.show_bboxes_checkbox)
+        toggles_layout.addWidget(self.show_confidence_checkbox)
+        toggles_layout.addStretch()
+        preview_layout.addLayout(toggles_layout)
+
+        self.summary_label = QLabel("Select a detection result to preview.")
+        self.summary_label.setWordWrap(True)
+        preview_layout.addWidget(self.summary_label)
+
+        preview_group.setLayout(preview_layout)
+        right_layout.addWidget(preview_group)
+        right_container.setLayout(right_layout)
+
+        splitter.addWidget(left_container)
+        splitter.addWidget(right_container)
+        splitter.setStretchFactor(0, 1)
+        splitter.setStretchFactor(1, 2)
+
+        layout.addWidget(splitter)
         self.setLayout(layout)
 
     def refresh(self):
-        """Refresh the tab."""
-        pass
+        """Refresh the detection list and preview."""
+        self._load_detection_summary()
+        self._populate_results_table()
+        self.current_selection = None
+        self.current_image = None
+        self.current_detections = []
+        self.preview_canvas.clear()
+        self.summary_label.setText("Select a detection result to preview.")
+
+    def _load_detection_summary(self):
+        """Load latest detection summaries grouped by image + model."""
+        try:
+            detections = self.db_manager.get_detections(limit=500)
+            summary_map: Dict[tuple, Dict] = {}
+
+            for det in detections:
+                key = (det["image_id"], det["model_id"])
+                metadata = det.get("metadata") or {}
+                entry = summary_map.setdefault(
+                    key,
+                    {
+                        "image_id": det["image_id"],
+                        "model_id": det["model_id"],
+                        "image_path": det.get("image_path"),
+                        "image_filename": det.get("image_filename")
+                        or det.get("image_path"),
+                        "model_name": det.get("model_name", ""),
+                        "model_version": det.get("model_version", ""),
+                        "last_detected": det.get("detected_at"),
+                        "count": 0,
+                        "classes": set(),
+                        "source_path": metadata.get("source_path"),
+                        "repository_root": metadata.get("repository_root"),
+                    },
+                )
+
+                entry["count"] += 1
+                if det.get("detected_at") and (
+                    not entry.get("last_detected")
+                    or str(det.get("detected_at")) > str(entry.get("last_detected"))
+                ):
+                    entry["last_detected"] = det.get("detected_at")
+                if det.get("class_name"):
+                    entry["classes"].add(det["class_name"])
+                if metadata.get("source_path") and not entry.get("source_path"):
+                    entry["source_path"] = metadata.get("source_path")
+                if metadata.get("repository_root") and not entry.get("repository_root"):
+                    entry["repository_root"] = metadata.get("repository_root")
+
+            self.detection_summary = sorted(
+                summary_map.values(),
+                key=lambda x: str(x.get("last_detected") or ""),
+                reverse=True,
+            )
+        except Exception as e:
+            logger.error(f"Failed to load detection summary: {e}")
+            QMessageBox.critical(
+                self,
+                "Error",
+                f"Failed to load detection results:\n{str(e)}",
+            )
+            self.detection_summary = []
+
+    def _populate_results_table(self):
+        """Populate the table widget with detection summaries."""
+        self.results_table.setRowCount(len(self.detection_summary))
+
+        for row, entry in enumerate(self.detection_summary):
+            model_label = f"{entry['model_name']} {entry['model_version']}".strip()
+            class_list = (
+                ", ".join(sorted(entry["classes"])) if entry["classes"] else "-"
+            )
+
+            items = [
+                QTableWidgetItem(entry.get("image_filename", "")),
+                QTableWidgetItem(model_label),
+                QTableWidgetItem(str(entry.get("count", 0))),
+                QTableWidgetItem(class_list),
+                QTableWidgetItem(str(entry.get("last_detected") or "")),
+            ]
+
+            for col, item in enumerate(items):
+                item.setData(Qt.UserRole, row)
+                self.results_table.setItem(row, col, item)
+
+        self.results_table.clearSelection()
+
+    def _on_result_selected(self):
+        """Handle selection changes in the detection table."""
+        selected_items = self.results_table.selectedItems()
+        if not selected_items:
+            return
+
+        row = selected_items[0].data(Qt.UserRole)
+        if row is None or row >= len(self.detection_summary):
+            return
+
+        entry = self.detection_summary[row]
+        if (
+            self.current_selection
+            and self.current_selection.get("image_id") == entry["image_id"]
+            and self.current_selection.get("model_id") == entry["model_id"]
+        ):
+            return
+
+        self.current_selection = entry
+
+        image_path = self._resolve_image_path(entry)
+        if not image_path:
+            QMessageBox.warning(
+                self,
+                "Image Not Found",
+                "Unable to locate the image file for this detection.",
+            )
+            return
+
+        try:
+            self.current_image = Image(image_path)
+            self.preview_canvas.load_image(self.current_image)
+        except ImageLoadError as e:
+            logger.error(f"Failed to load image '{image_path}': {e}")
+            QMessageBox.critical(
+                self,
+                "Image Error",
+                f"Failed to load image for preview:\n{str(e)}",
+            )
+            return
+
+        self._load_detections_for_selection(entry)
+        self._apply_detection_overlays()
+        self._update_summary_label(entry)
+
+    def _load_detections_for_selection(self, entry: Dict):
+        """Load detection records for the selected image/model pair."""
+        self.current_detections = []
+        if not entry:
+            return
+
+        try:
+            filters = {"image_id": entry["image_id"], "model_id": entry["model_id"]}
+            self.current_detections = self.db_manager.get_detections(filters)
+        except Exception as e:
+            logger.error(f"Failed to load detections for preview: {e}")
+            QMessageBox.critical(
+                self,
+                "Error",
+                f"Failed to load detections for this image:\n{str(e)}",
+            )
+            self.current_detections = []
+
+    def _apply_detection_overlays(self):
+        """Draw detections onto the preview canvas based on current toggles."""
+        self.preview_canvas.clear_annotations()
+        self.preview_canvas.set_show_bboxes(self.show_bboxes_checkbox.isChecked())
+
+        if not self.current_detections or not self.current_image:
+            return
+
+        for det in self.current_detections:
+            color = self._get_class_color(det.get("class_name"))
+
+            if self.show_masks_checkbox.isChecked() and det.get("segmentation_mask"):
+                mask_points = self._convert_mask(det["segmentation_mask"])
+                if mask_points:
+                    self.preview_canvas.draw_saved_polyline(mask_points, color)
+
+            bbox = [
+                det.get("x_min"),
+                det.get("y_min"),
+                det.get("x_max"),
+                det.get("y_max"),
+            ]
+            if all(v is not None for v in bbox):
+                label = None
+                if self.show_confidence_checkbox.isChecked():
+                    confidence = det.get("confidence")
+                    if confidence is not None:
+                        label = f"{confidence:.2f}"
+                self.preview_canvas.draw_saved_bbox(bbox, color, label=label)
+
+    def _convert_mask(self, mask_points: List[List[float]]) -> List[List[float]]:
+        """Convert stored [x, y] masks to [y, x] format for the canvas."""
+        converted = []
+        for point in mask_points:
+            if len(point) >= 2:
+                x, y = point[0], point[1]
+                converted.append([y, x])
+        return converted
+
+    def _toggle_bboxes(self):
+        """Update bounding box visibility on the canvas."""
+        self.preview_canvas.set_show_bboxes(self.show_bboxes_checkbox.isChecked())
+        # Re-render to respect show/hide when toggled
+        self._apply_detection_overlays()
+
+    def _update_summary_label(self, entry: Dict):
+        """Display textual summary for the selected detection run."""
+        classes = ", ".join(sorted(entry.get("classes", []))) or "-"
+        summary_text = (
+            f"Image: {entry.get('image_filename', 'unknown')}\n"
+            f"Model: {entry.get('model_name', '')} {entry.get('model_version', '')}\n"
+            f"Detections: {entry.get('count', 0)}\n"
+            f"Classes: {classes}\n"
+            f"Last Updated: {entry.get('last_detected', 'n/a')}"
+        )
+        self.summary_label.setText(summary_text)
+
+    def _resolve_image_path(self, entry: Dict) -> Optional[str]:
+        """Resolve an image path using metadata, cache, and repository hints."""
+        relative_path = entry.get("image_path") if entry else None
+        cache_key = relative_path or entry.get("source_path")
+        if cache_key and cache_key in self._image_path_cache:
+            cached = Path(self._image_path_cache[cache_key])
+            if cached.exists():
+                return self._image_path_cache[cache_key]
+            del self._image_path_cache[cache_key]
+
+        candidates = []
+        source_path = entry.get("source_path") if entry else None
+        if source_path:
+            candidates.append(Path(source_path))
+
+        repo_roots = []
+        if entry.get("repository_root"):
+            repo_roots.append(entry["repository_root"])
+        config_repo = self.config_manager.get_image_repository_path()
+        if config_repo:
+            repo_roots.append(config_repo)
+
+        for root in repo_roots:
+            if relative_path:
+                candidates.append(Path(root) / relative_path)
+
+        if relative_path:
+            candidates.append(Path(relative_path))
+
+        for candidate in candidates:
+            try:
+                if candidate and candidate.exists():
+                    resolved = str(candidate.resolve())
+                    if cache_key:
+                        self._image_path_cache[cache_key] = resolved
+                    return resolved
+            except Exception:
+                continue
+
+        # Fallback: search by filename in known roots
+        filename = Path(relative_path).name if relative_path else None
+        if filename:
+            search_roots = [Path(root) for root in repo_roots if root]
+            if not search_roots:
+                search_roots = [Path("data")]
+            match = self._search_in_roots(filename, search_roots)
+            if match:
+                resolved = str(match.resolve())
+                if cache_key:
+                    self._image_path_cache[cache_key] = resolved
+                return resolved
+
+        return None
+
+    def _search_in_roots(self, filename: str, roots: List[Path]) -> Optional[Path]:
+        """Search for a file name within a list of root directories."""
+        for root in roots:
+            try:
+                if not root.exists():
+                    continue
+                for candidate in root.rglob(filename):
+                    return candidate
+            except Exception as e:
+                logger.debug(f"Error searching for {filename} in {root}: {e}")
+        return None
+
+    def _get_class_color(self, class_name: Optional[str]) -> str:
+        """Return consistent color hex for a class name."""
+        if not class_name:
+            return "#FF6B6B"
+
+        color_map = self.config_manager.get_bbox_colors()
+        if class_name in color_map:
+            return color_map[class_name]
+
+        # Deterministic fallback color based on hash
+        palette = [
+            "#FF6B6B",
+            "#4ECDC4",
+            "#FFD166",
+            "#1D3557",
+            "#F4A261",
+            "#E76F51",
+        ]
+        return palette[hash(class_name) % len(palette)]

src/gui/tabs/training_tab.py

@@ -10,7 +10,6 @@ from pathlib import Path
 from typing import Any, Dict, List, Optional, Tuple
 
 import yaml
-from PIL import Image as PILImage
 from PySide6.QtCore import Qt, QThread, Signal
 from PySide6.QtWidgets import (
     QWidget,
@@ -28,24 +27,20 @@ from PySide6.QtWidgets import (
     QProgressBar,
     QSpinBox,
     QDoubleSpinBox,
+    QCheckBox,
+    QScrollArea,
 )
 
 from src.database.db_manager import DatabaseManager
 from src.model.yolo_wrapper import YOLOWrapper
 from src.utils.config_manager import ConfigManager
+from src.utils.image import Image
 from src.utils.logger import get_logger
 
 
 logger = get_logger(__name__)
 
-DEFAULT_IMAGE_EXTENSIONS = {
-    ".jpg",
-    ".jpeg",
-    ".png",
-    ".tif",
-    ".tiff",
-    ".bmp",
-}
+DEFAULT_IMAGE_EXTENSIONS = set(Image.SUPPORTED_EXTENSIONS)
 
 
 class TrainingWorker(QThread):
@@ -67,6 +62,8 @@ class TrainingWorker(QThread):
         save_dir: str,
         run_name: str,
         parent: Optional[QThread] = None,
+        stage_plan: Optional[List[Dict[str, Any]]] = None,
+        total_epochs: Optional[int] = None,
     ):
         super().__init__(parent)
         self.data_yaml = data_yaml
@@ -78,6 +75,27 @@ class TrainingWorker(QThread):
         self.lr0 = lr0
         self.save_dir = save_dir
         self.run_name = run_name
+        self.stage_plan = stage_plan or [
+            {
+                "label": "Single Stage",
+                "model_path": base_model,
+                "use_previous_best": False,
+                "params": {
+                    "epochs": epochs,
+                    "batch": batch,
+                    "imgsz": imgsz,
+                    "patience": patience,
+                    "lr0": lr0,
+                    "freeze": 0,
+                    "name": run_name,
+                },
+            }
+        ]
+        computed_total = sum(
+            max(0, int((stage.get("params") or {}).get("epochs", 0)))
+            for stage in self.stage_plan
+        )
+        self.total_epochs = total_epochs if total_epochs else computed_total or epochs
         self._stop_requested = False
 
     def stop(self):
@@ -86,36 +104,98 @@ class TrainingWorker(QThread):
         self.requestInterruption()
 
     def run(self):
-        """Execute YOLO training and emit progress/finished signals."""
-        wrapper = YOLOWrapper(self.base_model)
+        """Execute YOLO training over one or more stages and emit progress/finished signals."""
 
-        def on_epoch_end(trainer):
-            current_epoch = getattr(trainer, "epoch", 0) + 1
-            metrics: Dict[str, float] = {}
-            loss_items = getattr(trainer, "loss_items", None)
-            if loss_items:
-                metrics["loss"] = float(loss_items[-1])
-            self.progress.emit(current_epoch, self.epochs, metrics)
-            if self.isInterruptionRequested() or self._stop_requested:
-                setattr(trainer, "stop_training", True)
+        completed_epochs = 0
+        stage_history: List[Dict[str, Any]] = []
+        last_stage_results: Optional[Dict[str, Any]] = None
 
-        callbacks = {"on_fit_epoch_end": on_epoch_end}
+        for stage_index, stage in enumerate(self.stage_plan, start=1):
+            if self._stop_requested or self.isInterruptionRequested():
+                break
 
-        try:
-            results = wrapper.train(
-                data_yaml=self.data_yaml,
-                epochs=self.epochs,
-                imgsz=self.imgsz,
-                batch=self.batch,
-                patience=self.patience,
-                save_dir=self.save_dir,
-                name=self.run_name,
-                lr0=self.lr0,
-                callbacks=callbacks,
+            stage_label = stage.get("label") or f"Stage {stage_index}"
+            stage_params = dict(stage.get("params") or {})
+            stage_epochs = int(stage_params.get("epochs", self.epochs))
+            if stage_epochs <= 0:
+                stage_epochs = 1
+            batch = int(stage_params.get("batch", self.batch))
+            imgsz = int(stage_params.get("imgsz", self.imgsz))
+            patience = int(stage_params.get("patience", self.patience))
+            lr0 = float(stage_params.get("lr0", self.lr0))
+            freeze = int(stage_params.get("freeze", 0))
+            run_name = stage_params.get("name") or f"{self.run_name}_stage{stage_index}"
+
+            weights_path = stage.get("model_path") or self.base_model
+            if stage.get("use_previous_best") and last_stage_results:
+                weights_path = (
+                    last_stage_results.get("best_model_path")
+                    or last_stage_results.get("last_model_path")
+                    or weights_path
+                )
+
+            wrapper = YOLOWrapper(weights_path)
+            stage_offset = completed_epochs
+
+            def on_epoch_end(trainer, offset=stage_offset):
+                current_epoch = getattr(trainer, "epoch", 0) + 1
+                metrics: Dict[str, float] = {}
+                loss_items = getattr(trainer, "loss_items", None)
+                if loss_items:
+                    metrics["loss"] = float(loss_items[-1])
+                absolute_epoch = min(
+                    max(1, offset + current_epoch),
+                    max(1, self.total_epochs),
+                )
+                self.progress.emit(absolute_epoch, self.total_epochs, metrics)
+                if self.isInterruptionRequested() or self._stop_requested:
+                    setattr(trainer, "stop_training", True)
+
+            callbacks = {"on_fit_epoch_end": on_epoch_end}
+
+            try:
+                stage_result = wrapper.train(
+                    data_yaml=self.data_yaml,
+                    epochs=stage_epochs,
+                    imgsz=imgsz,
+                    batch=batch,
+                    patience=patience,
+                    save_dir=self.save_dir,
+                    name=run_name,
+                    lr0=lr0,
+                    callbacks=callbacks,
+                    freeze=freeze,
+                )
+            except Exception as exc:
+                self.error.emit(str(exc))
+                return
+
+            stage_history.append(
+                {
+                    "label": stage_label,
+                    "params": stage_params,
+                    "weights_used": weights_path,
+                    "results": stage_result,
+                }
             )
-            self.finished.emit(results)
-        except Exception as exc:
-            self.error.emit(str(exc))
+            last_stage_results = stage_result
+            completed_epochs += stage_epochs
+
+        final_payload: Dict[str, Any]
+        if last_stage_results:
+            final_payload = dict(last_stage_results)
+        else:
+            final_payload = {
+                "success": False,
+                "message": "Training stopped before any stage completed.",
+            }
+
+        final_payload["stage_results"] = stage_history
+        final_payload["total_epochs_completed"] = completed_epochs
+        final_payload["total_epochs_planned"] = self.total_epochs
+        final_payload["stages_completed"] = len(stage_history)
+
+        self.finished.emit(final_payload)
 
 
 class TrainingTab(QWidget):
@@ -146,12 +226,23 @@ class TrainingTab(QWidget):
 
     def _setup_ui(self):
         """Setup user interface."""
-        layout = QVBoxLayout()
+        # Create a container widget for all content
+        container = QWidget()
+        container_layout = QVBoxLayout(container)
 
-        layout.addWidget(self._create_dataset_group())
-        layout.addWidget(self._create_training_controls_group())
-        layout.addStretch()
-        self.setLayout(layout)
+        container_layout.addWidget(self._create_dataset_group())
+        container_layout.addWidget(self._create_training_controls_group())
+        container_layout.addStretch()
+
+        # Create scroll area and set the container as its widget
+        scroll_area = QScrollArea()
+        scroll_area.setWidget(container)
+        scroll_area.setWidgetResizable(True)
+
+        # Set main layout with scroll area
+        main_layout = QVBoxLayout(self)
+        main_layout.setContentsMargins(0, 0, 0, 0)
+        main_layout.addWidget(scroll_area)
 
         self._discover_datasets()
         self._load_saved_dataset()
@@ -249,13 +340,26 @@ class TrainingTab(QWidget):
         default_base_model = self.config_manager.get(
             "models.default_base_model", "yolov8s-seg.pt"
         )
+        base_model_choices = self.config_manager.get("models.base_model_choices", [])
+
+        self.base_model_combo = QComboBox()
+        self.base_model_combo.addItem("Custom path…", "")
+        for choice in base_model_choices:
+            self.base_model_combo.addItem(choice, choice)
+        self.base_model_combo.currentIndexChanged.connect(
+            self._on_base_model_preset_changed
+        )
+        form_layout.addRow("Base Model Preset:", self.base_model_combo)
+
         base_model_layout = QHBoxLayout()
         self.base_model_edit = QLineEdit(default_base_model)
+        self.base_model_edit.editingFinished.connect(self._on_base_model_path_edited)
         base_model_layout.addWidget(self.base_model_edit)
         self.base_model_browse_button = QPushButton("Browse…")
         self.base_model_browse_button.clicked.connect(self._browse_base_model)
         base_model_layout.addWidget(self.base_model_browse_button)
         form_layout.addRow("Base Model (.pt):", base_model_layout)
+        self._sync_base_model_preset_selection(default_base_model)
 
         models_dir = self.config_manager.get("models.models_directory", "data/models")
         save_dir_layout = QHBoxLayout()
@@ -298,6 +402,9 @@ class TrainingTab(QWidget):
 
         group_layout.addLayout(form_layout)
 
+        self.two_stage_group = self._create_two_stage_group(training_defaults)
+        group_layout.addWidget(self.two_stage_group)
+
         button_layout = QHBoxLayout()
         self.start_training_button = QPushButton("Start Training")
         self.start_training_button.clicked.connect(self._start_training)
@@ -322,6 +429,134 @@ class TrainingTab(QWidget):
         group.setLayout(group_layout)
         return group
 
+    def _create_two_stage_group(self, training_defaults: Dict[str, Any]) -> QGroupBox:
+        group = QGroupBox("Two-Stage Fine-Tuning")
+        group_layout = QVBoxLayout()
+
+        self.two_stage_checkbox = QCheckBox("Enable staged head-only + full fine-tune")
+        two_stage_defaults = (
+            training_defaults.get("two_stage", {}) if training_defaults else {}
+        )
+        self.two_stage_checkbox.setChecked(
+            bool(two_stage_defaults.get("enabled", False))
+        )
+        self.two_stage_checkbox.toggled.connect(self._on_two_stage_toggled)
+        group_layout.addWidget(self.two_stage_checkbox)
+
+        self.two_stage_controls_widget = QWidget()
+        controls_layout = QVBoxLayout()
+        controls_layout.setContentsMargins(0, 0, 0, 0)
+        controls_layout.setSpacing(8)
+
+        stage1_group = QGroupBox("Stage 1 — Head-only stabilization")
+        stage1_form = QFormLayout()
+        stage1_defaults = two_stage_defaults.get("stage1", {})
+
+        self.stage1_epochs_spin = QSpinBox()
+        self.stage1_epochs_spin.setRange(1, 500)
+        self.stage1_epochs_spin.setValue(int(stage1_defaults.get("epochs", 20)))
+        stage1_form.addRow("Epochs:", self.stage1_epochs_spin)
+
+        self.stage1_lr_spin = QDoubleSpinBox()
+        self.stage1_lr_spin.setDecimals(5)
+        self.stage1_lr_spin.setRange(0.00001, 0.1)
+        self.stage1_lr_spin.setSingleStep(0.0005)
+        self.stage1_lr_spin.setValue(float(stage1_defaults.get("lr0", 0.0005)))
+        stage1_form.addRow("Learning Rate:", self.stage1_lr_spin)
+
+        self.stage1_patience_spin = QSpinBox()
+        self.stage1_patience_spin.setRange(1, 200)
+        self.stage1_patience_spin.setValue(int(stage1_defaults.get("patience", 10)))
+        stage1_form.addRow("Patience:", self.stage1_patience_spin)
+
+        self.stage1_freeze_spin = QSpinBox()
+        self.stage1_freeze_spin.setRange(0, 24)
+        self.stage1_freeze_spin.setValue(int(stage1_defaults.get("freeze", 10)))
+        stage1_form.addRow("Freeze layers:", self.stage1_freeze_spin)
+
+        stage1_group.setLayout(stage1_form)
+        controls_layout.addWidget(stage1_group)
+
+        stage2_group = QGroupBox("Stage 2 — Full fine-tuning")
+        stage2_form = QFormLayout()
+        stage2_defaults = two_stage_defaults.get("stage2", {})
+
+        self.stage2_epochs_spin = QSpinBox()
+        self.stage2_epochs_spin.setRange(1, 2000)
+        self.stage2_epochs_spin.setValue(int(stage2_defaults.get("epochs", 150)))
+        stage2_form.addRow("Epochs:", self.stage2_epochs_spin)
+
+        self.stage2_lr_spin = QDoubleSpinBox()
+        self.stage2_lr_spin.setDecimals(5)
+        self.stage2_lr_spin.setRange(0.00001, 0.1)
+        self.stage2_lr_spin.setSingleStep(0.0005)
+        self.stage2_lr_spin.setValue(float(stage2_defaults.get("lr0", 0.0003)))
+        stage2_form.addRow("Learning Rate:", self.stage2_lr_spin)
+
+        self.stage2_patience_spin = QSpinBox()
+        self.stage2_patience_spin.setRange(1, 200)
+        self.stage2_patience_spin.setValue(int(stage2_defaults.get("patience", 30)))
+        stage2_form.addRow("Patience:", self.stage2_patience_spin)
+
+        stage2_group.setLayout(stage2_form)
+        controls_layout.addWidget(stage2_group)
+
+        helper_label = QLabel(
+            "When enabled, staged hyperparameters override the global epochs/patience/lr."
+        )
+        helper_label.setWordWrap(True)
+        controls_layout.addWidget(helper_label)
+
+        self.two_stage_controls_widget.setLayout(controls_layout)
+        group_layout.addWidget(self.two_stage_controls_widget)
+
+        group.setLayout(group_layout)
+        self._on_two_stage_toggled(self.two_stage_checkbox.isChecked())
+        return group
+
+    def _on_two_stage_toggled(self, checked: bool):
+        self._refresh_two_stage_controls_enabled(checked)
+
+    def _refresh_two_stage_controls_enabled(self, checked: Optional[bool] = None):
+        if not hasattr(self, "two_stage_controls_widget"):
+            return
+        desired_state = checked
+        if desired_state is None:
+            desired_state = self.two_stage_checkbox.isChecked()
+        can_edit = self.two_stage_checkbox.isEnabled()
+        self.two_stage_controls_widget.setEnabled(bool(desired_state and can_edit))
+
+    def _on_base_model_preset_changed(self, index: int):
+        preset_value = self.base_model_combo.itemData(index)
+        if preset_value:
+            self.base_model_edit.setText(str(preset_value))
+        elif index == 0:
+            self.base_model_edit.setFocus()
+
+    def _on_base_model_path_edited(self):
+        self._sync_base_model_preset_selection(self.base_model_edit.text().strip())
+
+    def _sync_base_model_preset_selection(self, model_path: str):
+        if not hasattr(self, "base_model_combo"):
+            return
+        normalized = (model_path or "").strip()
+        target_index = 0
+        for idx in range(1, self.base_model_combo.count()):
+            preset_value = self.base_model_combo.itemData(idx)
+            if not preset_value:
+                continue
+            if normalized == preset_value:
+                target_index = idx
+                break
+            if normalized.endswith(f"/{preset_value}") or normalized.endswith(
+                f"\\{preset_value}"
+            ):
+                target_index = idx
+                break
+        self.base_model_combo.blockSignals(True)
+        self.base_model_combo.setCurrentIndex(target_index)
+        self.base_model_combo.blockSignals(False)
+
     def _get_dataset_search_roots(self) -> List[Path]:
         roots: List[Path] = []
         default_root = Path("data/datasets").expanduser()
@@ -346,6 +581,7 @@ class TrainingTab(QWidget):
                 for yaml_path in root.rglob("*.yaml"):
                     if yaml_path.name.lower() not in {"data.yaml", "dataset.yaml"}:
                         continue
+
                     discovered.append(yaml_path.resolve())
             except Exception as exc:
                 logger.warning(f"Unable to scan {root}: {exc}")
@@ -964,6 +1200,90 @@ class TrainingTab(QWidget):
         self._build_rgb_dataset(cache_root, dataset_info)
         return rgb_yaml
 
+    def _compose_stage_plan(self, params: Dict[str, Any]) -> List[Dict[str, Any]]:
+        two_stage = params.get("two_stage") or {}
+        base_stage = {
+            "label": "Single Stage",
+            "model_path": params["base_model"],
+            "use_previous_best": False,
+            "params": {
+                "epochs": params["epochs"],
+                "batch": params["batch"],
+                "imgsz": params["imgsz"],
+                "patience": params["patience"],
+                "lr0": params["lr0"],
+                "freeze": 0,
+                "name": params["run_name"],
+            },
+        }
+
+        if not two_stage.get("enabled"):
+            return [base_stage]
+
+        stage_plan: List[Dict[str, Any]] = []
+        stage1 = two_stage.get("stage1", {})
+        stage2 = two_stage.get("stage2", {})
+
+        stage_plan.append(
+            {
+                "label": "Stage 1 — Head-only",
+                "model_path": params["base_model"],
+                "use_previous_best": False,
+                "params": {
+                    "epochs": stage1.get("epochs", params["epochs"]),
+                    "batch": params["batch"],
+                    "imgsz": params["imgsz"],
+                    "patience": stage1.get("patience", params["patience"]),
+                    "lr0": stage1.get("lr0", params["lr0"]),
+                    "freeze": stage1.get("freeze", 0),
+                    "name": f"{params['run_name']}_head_ft",
+                },
+            }
+        )
+
+        stage_plan.append(
+            {
+                "label": "Stage 2 — Full",
+                "model_path": params["base_model"],
+                "use_previous_best": True,
+                "params": {
+                    "epochs": stage2.get("epochs", params["epochs"]),
+                    "batch": params["batch"],
+                    "imgsz": params["imgsz"],
+                    "patience": stage2.get("patience", params["patience"]),
+                    "lr0": stage2.get("lr0", params["lr0"]),
+                    "freeze": stage2.get("freeze", 0),
+                    "name": f"{params['run_name']}_full_ft",
+                },
+            }
+        )
+
+        return stage_plan
+
+    def _calculate_total_stage_epochs(self, stage_plan: List[Dict[str, Any]]) -> int:
+        total = 0
+        for stage in stage_plan:
+            params = stage.get("params") or {}
+            try:
+                stage_epochs = int(params.get("epochs", 0))
+            except (TypeError, ValueError):
+                stage_epochs = 0
+            if stage_epochs > 0:
+                total += stage_epochs
+        return total
+
+    def _log_stage_plan(self, stage_plan: List[Dict[str, Any]]):
+        for index, stage in enumerate(stage_plan, start=1):
+            stage_label = stage.get("label") or f"Stage {index}"
+            params = stage.get("params") or {}
+            epochs = params.get("epochs", "?")
+            lr0 = params.get("lr0", "?")
+            patience = params.get("patience", "?")
+            freeze = params.get("freeze", 0)
+            self._append_training_log(
+                f"    • {stage_label}: epochs={epochs}, lr0={lr0}, patience={patience}, freeze={freeze}"
+            )
+
     def _get_rgb_cache_root(self, dataset_yaml: Path) -> Path:
         cache_base = Path("data/datasets/_rgb_cache")
         cache_base.mkdir(parents=True, exist_ok=True)
@@ -984,8 +1304,8 @@ class TrainingTab(QWidget):
         if not sample_image:
             return False
         try:
-            with PILImage.open(sample_image) as img:
-                return img.mode.upper() != "RGB"
+            img = Image(sample_image)
+            return img.pil_image.mode.upper() != "RGB"
         except Exception as exc:
             logger.warning(f"Failed to inspect image {sample_image}: {exc}")
             return False
@@ -1045,9 +1365,13 @@ class TrainingTab(QWidget):
             dst = dst_dir / relative
             dst.parent.mkdir(parents=True, exist_ok=True)
             try:
-                with PILImage.open(src) as img:
-                    rgb_img = img.convert("RGB")
-                    rgb_img.save(dst)
+                img_obj = Image(src)
+                pil_img = img_obj.pil_image
+                if len(pil_img.getbands()) == 1:
+                    rgb_img = img_obj.convert_grayscale_to_rgb_preserve_range()
+                else:
+                    rgb_img = pil_img.convert("RGB")
+                rgb_img.save(dst)
             except Exception as exc:
                 logger.warning(f"Failed to convert {src} to RGB: {exc}")
 
@@ -1085,6 +1409,21 @@ class TrainingTab(QWidget):
         save_dir_path.mkdir(parents=True, exist_ok=True)
         run_name = f"{model_name}_{model_version}".replace(" ", "_")
 
+        two_stage_config = {
+            "enabled": self.two_stage_checkbox.isChecked(),
+            "stage1": {
+                "epochs": self.stage1_epochs_spin.value(),
+                "lr0": self.stage1_lr_spin.value(),
+                "patience": self.stage1_patience_spin.value(),
+                "freeze": self.stage1_freeze_spin.value(),
+            },
+            "stage2": {
+                "epochs": self.stage2_epochs_spin.value(),
+                "lr0": self.stage2_lr_spin.value(),
+                "patience": self.stage2_patience_spin.value(),
+            },
+        }
+
         return {
             "model_name": model_name,
             "model_version": model_version,
@@ -1096,6 +1435,7 @@ class TrainingTab(QWidget):
             "imgsz": self.imgsz_spin.value(),
             "patience": self.patience_spin.value(),
             "lr0": self.lr_spin.value(),
+            "two_stage": two_stage_config,
         }
 
     def _start_training(self):
@@ -1137,15 +1477,25 @@ class TrainingTab(QWidget):
             )
 
         params = self._collect_training_params()
+        stage_plan = self._compose_stage_plan(params)
+        params["stage_plan"] = stage_plan
+        total_planned_epochs = (
+            self._calculate_total_stage_epochs(stage_plan) or params["epochs"]
+        )
+        params["total_planned_epochs"] = total_planned_epochs
         self._active_training_params = params
         self._training_cancelled = False
 
+        if len(stage_plan) > 1:
+            self._append_training_log("Two-stage fine-tuning schedule:")
+            self._log_stage_plan(stage_plan)
+
         self._append_training_log(
             f"Starting training run '{params['run_name']}' using {params['base_model']}"
         )
 
         self.training_progress_bar.setVisible(True)
-        self.training_progress_bar.setMaximum(params["epochs"])
+        self.training_progress_bar.setMaximum(max(1, total_planned_epochs))
         self.training_progress_bar.setValue(0)
         self._set_training_state(True)
 
@@ -1159,6 +1509,8 @@ class TrainingTab(QWidget):
             lr0=params["lr0"],
             save_dir=params["save_dir"],
             run_name=params["run_name"],
+            stage_plan=stage_plan,
+            total_epochs=total_planned_epochs,
         )
         self.training_worker.progress.connect(self._on_training_progress)
         self.training_worker.finished.connect(self._on_training_finished)
@@ -1283,14 +1635,22 @@ class TrainingTab(QWidget):
         if not model_path:
             raise ValueError("Training results did not include a model path.")
 
+        effective_epochs = params.get("total_planned_epochs", params["epochs"])
         training_params = {
-            "epochs": params["epochs"],
+            "epochs": effective_epochs,
             "batch": params["batch"],
             "imgsz": params["imgsz"],
             "patience": params["patience"],
             "lr0": params["lr0"],
             "run_name": params["run_name"],
+            "two_stage": params.get("two_stage"),
         }
+        if params.get("stage_plan"):
+            training_params["stage_plan"] = params["stage_plan"]
+        if results.get("stage_results"):
+            training_params["stage_results"] = results["stage_results"]
+        if results.get("total_epochs_completed") is not None:
+            training_params["epochs_completed"] = results["total_epochs_completed"]
 
         model_id = self.db_manager.add_model(
             model_name=params["model_name"],
@@ -1315,6 +1675,7 @@ class TrainingTab(QWidget):
         self.rescan_button.setEnabled(not is_training)
         self.model_name_edit.setEnabled(not is_training)
         self.model_version_edit.setEnabled(not is_training)
+        self.base_model_combo.setEnabled(not is_training)
         self.base_model_edit.setEnabled(not is_training)
         self.base_model_browse_button.setEnabled(not is_training)
         self.save_dir_edit.setEnabled(not is_training)
@@ -1324,6 +1685,8 @@ class TrainingTab(QWidget):
         self.imgsz_spin.setEnabled(not is_training)
         self.patience_spin.setEnabled(not is_training)
         self.lr_spin.setEnabled(not is_training)
+        self.two_stage_checkbox.setEnabled(not is_training)
+        self._refresh_two_stage_controls_enabled()
 
     def _append_training_log(self, message: str):
         timestamp = datetime.now().strftime("%H:%M:%S")
@@ -1339,6 +1702,7 @@ class TrainingTab(QWidget):
         )
         if file_path:
             self.base_model_edit.setText(file_path)
+            self._sync_base_model_preset_selection(file_path)
 
     def _browse_save_dir(self):
         start_path = self.save_dir_edit.text().strip() or "data/models"

src/gui/widgets/annotation_canvas_widget.py

@@ -16,8 +16,9 @@ from PySide6.QtGui import (
     QKeyEvent,
     QMouseEvent,
     QPaintEvent,
+    QPolygonF,
 )
-from PySide6.QtCore import Qt, QEvent, Signal, QPoint
+from PySide6.QtCore import Qt, QEvent, Signal, QPoint, QPointF, QRect
 from typing import Any, Dict, List, Optional, Tuple
 
 from src.utils.image import Image, ImageLoadError
@@ -246,10 +247,10 @@ class AnnotationCanvasWidget(QWidget):
             return
 
         try:
-            # Get RGB image data
-            if self.current_image.channels == 3:
+            # Get image data in a format compatible with Qt
+            if self.current_image.channels in (3, 4):
                 image_data = self.current_image.get_rgb()
-                height, width, channels = image_data.shape
+                height, width = image_data.shape[:2]
             else:
                 image_data = self.current_image.get_grayscale()
                 height, width = image_data.shape
@@ -263,7 +264,7 @@ class AnnotationCanvasWidget(QWidget):
                 height,
                 bytes_per_line,
                 self.current_image.qtimage_format,
-            )
+            ).copy()  # Copy so Qt owns the buffer even after numpy array goes out of scope
 
             self.original_pixmap = QPixmap.fromImage(qimage)
 
@@ -496,8 +497,10 @@ class AnnotationCanvasWidget(QWidget):
                 )
 
             painter.setPen(pen)
-            for (x1, y1), (x2, y2) in zip(polyline[:-1], polyline[1:]):
-                painter.drawLine(int(x1), int(y1), int(x2), int(y2))
+            # Use QPolygonF for efficient polygon rendering (single call vs N-1 calls)
+            # drawPolygon() automatically closes the shape, ensuring proper visual closure
+            polygon = QPolygonF([QPointF(x, y) for x, y in polyline])
+            painter.drawPolygon(polygon)
 
         # Draw bounding boxes (dashed) if enabled
         if self.show_bboxes and self.original_pixmap is not None and self.bboxes:
@@ -529,6 +532,40 @@ class AnnotationCanvasWidget(QWidget):
                 painter.setPen(pen)
                 painter.drawRect(x_min, y_min, rect_width, rect_height)
 
+                label_text = meta.get("label")
+                if label_text:
+                    painter.save()
+                    font = painter.font()
+                    font.setPointSizeF(max(10.0, width + 4))
+                    painter.setFont(font)
+                    metrics = painter.fontMetrics()
+                    text_width = metrics.horizontalAdvance(label_text)
+                    text_height = metrics.height()
+                    padding = 4
+                    bg_width = text_width + padding * 2
+                    bg_height = text_height + padding * 2
+                    canvas_width = self.original_pixmap.width()
+                    canvas_height = self.original_pixmap.height()
+                    bg_x = max(0, min(x_min, canvas_width - bg_width))
+                    bg_y = y_min - bg_height
+                    if bg_y < 0:
+                        bg_y = min(y_min, canvas_height - bg_height)
+                        bg_y = max(0, bg_y)
+                    background_rect = QRect(bg_x, bg_y, bg_width, bg_height)
+                    background_color = QColor(pen_color)
+                    background_color.setAlpha(220)
+                    painter.fillRect(background_rect, background_color)
+                    text_color = QColor(0, 0, 0)
+                    if background_color.lightness() < 128:
+                        text_color = QColor(255, 255, 255)
+                    painter.setPen(text_color)
+                    painter.drawText(
+                        background_rect.adjusted(padding, padding, -padding, -padding),
+                        Qt.AlignLeft | Qt.AlignVCenter,
+                        label_text,
+                    )
+                    painter.restore()
+
         painter.end()
 
         self._update_display()
@@ -787,7 +824,13 @@ class AnnotationCanvasWidget(QWidget):
             f"Drew saved polyline with {len(polyline)} points in color {color}"
         )
 
-    def draw_saved_bbox(self, bbox: List[float], color: str, width: int = 3):
+    def draw_saved_bbox(
+        self,
+        bbox: List[float],
+        color: str,
+        width: int = 3,
+        label: Optional[str] = None,
+    ):
         """
         Draw a bounding box from database coordinates onto the annotation canvas.
 
@@ -796,6 +839,7 @@ class AnnotationCanvasWidget(QWidget):
                   in normalized coordinates (0-1)
             color: Color hex string (e.g., '#FF0000')
             width: Line width in pixels
+            label: Optional text label to render near the bounding box
         """
         if not self.annotation_pixmap or not self.original_pixmap:
             logger.warning("Cannot draw bounding box: no image loaded")
@@ -828,11 +872,11 @@ class AnnotationCanvasWidget(QWidget):
         self.bboxes.append(
             [float(x_min_norm), float(y_min_norm), float(x_max_norm), float(y_max_norm)]
         )
-        self.bbox_meta.append({"color": pen_color, "width": int(width)})
+        self.bbox_meta.append({"color": pen_color, "width": int(width), "label": label})
 
         # Store in all_strokes for consistency
         self.all_strokes.append(
-            {"bbox": bbox, "color": color, "alpha": 128, "width": width}
+            {"bbox": bbox, "color": color, "alpha": 128, "width": width, "label": label}
         )
 
         # Redraw overlay (polylines + all bounding boxes)

src/gui/widgets/image_display_widget.py

@@ -137,7 +137,7 @@ class ImageDisplayWidget(QWidget):
                 height,
                 bytes_per_line,
                 self.current_image.qtimage_format,
-            )
+            ).copy()  # Copy to ensure Qt owns its memory after this scope
 
             # Convert to pixmap
             pixmap = QPixmap.fromImage(qimage)

src/model/inference.py

@@ -5,12 +5,12 @@ Handles detection inference and result storage.
 
 from typing import List, Dict, Optional, Callable
 from pathlib import Path
-from PIL import Image
 import cv2
 import numpy as np
 
 from src.model.yolo_wrapper import YOLOWrapper
 from src.database.db_manager import DatabaseManager
+from src.utils.image import Image
 from src.utils.logger import get_logger
 from src.utils.file_utils import get_relative_path
 
@@ -42,6 +42,7 @@ class InferenceEngine:
         relative_path: str,
         conf: float = 0.25,
         save_to_db: bool = True,
+        repository_root: Optional[str] = None,
     ) -> Dict:
         """
         Detect objects in a single image.
@@ -51,49 +52,79 @@ class InferenceEngine:
             relative_path: Relative path from repository root
             conf: Confidence threshold
             save_to_db: Whether to save results to database
+            repository_root: Base directory used to compute relative_path (if known)
 
         Returns:
             Dictionary with detection results
         """
         try:
+            # Normalize storage path (fall back to absolute path when repo root is unknown)
+            stored_relative_path = relative_path
+            if not repository_root:
+                stored_relative_path = str(Path(image_path).resolve())
+
             # Get image dimensions
-            img = Image.open(image_path)
-            width, height = img.size
-            img.close()
+            img = Image(image_path)
+            width = img.width
+            height = img.height
 
             # Perform detection
             detections = self.yolo.predict(image_path, conf=conf)
 
             # Add/get image in database
             image_id = self.db_manager.get_or_create_image(
-                relative_path=relative_path,
+                relative_path=stored_relative_path,
                 filename=Path(image_path).name,
                 width=width,
                 height=height,
             )
 
-            # Save detections to database
-            if save_to_db and detections:
-                detection_records = []
-                for det in detections:
-                    # Use normalized bbox from detection
-                    bbox_normalized = det[
-                        "bbox_normalized"
-                    ]  # [x_min, y_min, x_max, y_max]
+            inserted_count = 0
+            deleted_count = 0
 
-                    record = {
-                        "image_id": image_id,
-                        "model_id": self.model_id,
-                        "class_name": det["class_name"],
-                        "bbox": tuple(bbox_normalized),
-                        "confidence": det["confidence"],
-                        "segmentation_mask": det.get("segmentation_mask"),
-                        "metadata": {"class_id": det["class_id"]},
-                    }
-                    detection_records.append(record)
+            # Save detections to database, replacing any previous results for this image/model
+            if save_to_db:
+                deleted_count = self.db_manager.delete_detections_for_image(
+                    image_id, self.model_id
+                )
+                if detections:
+                    detection_records = []
+                    for det in detections:
+                        # Use normalized bbox from detection
+                        bbox_normalized = det[
+                            "bbox_normalized"
+                        ]  # [x_min, y_min, x_max, y_max]
 
-                self.db_manager.add_detections_batch(detection_records)
-                logger.info(f"Saved {len(detection_records)} detections to database")
+                        metadata = {
+                            "class_id": det["class_id"],
+                            "source_path": str(Path(image_path).resolve()),
+                        }
+                        if repository_root:
+                            metadata["repository_root"] = str(
+                                Path(repository_root).resolve()
+                            )
+
+                        record = {
+                            "image_id": image_id,
+                            "model_id": self.model_id,
+                            "class_name": det["class_name"],
+                            "bbox": tuple(bbox_normalized),
+                            "confidence": det["confidence"],
+                            "segmentation_mask": det.get("segmentation_mask"),
+                            "metadata": metadata,
+                        }
+                        detection_records.append(record)
+
+                    inserted_count = self.db_manager.add_detections_batch(
+                        detection_records
+                    )
+                    logger.info(
+                        f"Saved {inserted_count} detections to database (replaced {deleted_count})"
+                    )
+                else:
+                    logger.info(
+                        f"Detection run removed {deleted_count} stale entries but produced no new detections"
+                    )
 
             return {
                 "success": True,
@@ -142,7 +173,12 @@ class InferenceEngine:
             rel_path = get_relative_path(image_path, repository_root)
 
             # Perform detection
-            result = self.detect_single(image_path, rel_path, conf)
+            result = self.detect_single(
+                image_path,
+                rel_path,
+                conf=conf,
+                repository_root=repository_root,
+            )
             results.append(result)
 
             # Update progress

src/model/yolo_wrapper.py

@@ -7,6 +7,9 @@ from ultralytics import YOLO
 from pathlib import Path
 from typing import Optional, List, Dict, Callable, Any
 import torch
+import tempfile
+import os
+from src.utils.image import Image
 from src.utils.logger import get_logger
 
 
@@ -77,7 +80,8 @@ class YOLOWrapper:
             Dictionary with training results
         """
         if self.model is None:
-            self.load_model()
+            if not self.load_model():
+                raise RuntimeError(f"Failed to load model from {self.model_path}")
 
         try:
             logger.info(f"Starting training: {name}")
@@ -119,7 +123,8 @@ class YOLOWrapper:
             Dictionary with validation metrics
         """
         if self.model is None:
-            self.load_model()
+            if not self.load_model():
+                raise RuntimeError(f"Failed to load model from {self.model_path}")
 
         try:
             logger.info(f"Starting validation on {split} split")
@@ -160,12 +165,15 @@ class YOLOWrapper:
             List of detection dictionaries
         """
         if self.model is None:
-            self.load_model()
+            if not self.load_model():
+                raise RuntimeError(f"Failed to load model from {self.model_path}")
+
+        prepared_source, cleanup_path = self._prepare_source(source)
 
         try:
             logger.info(f"Running inference on {source}")
             results = self.model.predict(
-                source=source,
+                source=prepared_source,
                 conf=conf,
                 iou=iou,
                 save=save,
@@ -182,6 +190,14 @@ class YOLOWrapper:
         except Exception as e:
             logger.error(f"Error during inference: {e}")
             raise
+        finally:
+            if 0:  # cleanup_path:
+                try:
+                    os.remove(cleanup_path)
+                except OSError as cleanup_error:
+                    logger.warning(
+                        f"Failed to delete temporary RGB image {cleanup_path}: {cleanup_error}"
+                    )
 
     def export(
         self, format: str = "onnx", output_path: Optional[str] = None, **kwargs
@@ -198,7 +214,8 @@ class YOLOWrapper:
             Path to exported model
         """
         if self.model is None:
-            self.load_model()
+            if not self.load_model():
+                raise RuntimeError(f"Failed to load model from {self.model_path}")
 
         try:
             logger.info(f"Exporting model to {format} format")
@@ -210,6 +227,38 @@ class YOLOWrapper:
             logger.error(f"Error exporting model: {e}")
             raise
 
+    def _prepare_source(self, source):
+        """Convert single-channel images to RGB temporarily for inference."""
+        cleanup_path = None
+
+        if isinstance(source, (str, Path)):
+            source_path = Path(source)
+            if source_path.is_file():
+                try:
+                    img_obj = Image(source_path)
+                    pil_img = img_obj.pil_image
+                    if len(pil_img.getbands()) == 1:
+                        rgb_img = img_obj.convert_grayscale_to_rgb_preserve_range()
+                    else:
+                        rgb_img = pil_img.convert("RGB")
+
+                    suffix = source_path.suffix or ".png"
+                    tmp = tempfile.NamedTemporaryFile(suffix=suffix, delete=False)
+                    tmp_path = tmp.name
+                    tmp.close()
+                    rgb_img.save(tmp_path)
+                    cleanup_path = tmp_path
+                    logger.info(
+                        f"Converted image {source_path} to RGB for inference at {tmp_path}"
+                    )
+                    return tmp_path, cleanup_path
+                except Exception as convert_error:
+                    logger.warning(
+                        f"Failed to preprocess {source_path} as RGB, continuing with original file: {convert_error}"
+                    )
+
+        return source, cleanup_path
+
     def _format_training_results(self, results) -> Dict[str, Any]:
         """Format training results into dictionary."""
         try:

src/utils/config_manager.py

@@ -7,6 +7,7 @@ import yaml
 from pathlib import Path
 from typing import Any, Dict, Optional
 from src.utils.logger import get_logger
+from src.utils.image import Image
 
 
 logger = get_logger(__name__)
@@ -46,18 +47,15 @@ class ConfigManager:
             "database": {"path": "data/detections.db"},
             "image_repository": {
                 "base_path": "",
-                "allowed_extensions": [
-                    ".jpg",
-                    ".jpeg",
-                    ".png",
-                    ".tif",
-                    ".tiff",
-                    ".bmp",
-                ],
+                "allowed_extensions": Image.SUPPORTED_EXTENSIONS,
             },
             "models": {
                 "default_base_model": "yolov8s-seg.pt",
                 "models_directory": "data/models",
+                "base_model_choices": [
+                    "yolov8s-seg.pt",
+                    "yolov11s-seg.pt",
+                ],
             },
             "training": {
                 "default_epochs": 100,
@@ -65,6 +63,20 @@ class ConfigManager:
                 "default_imgsz": 640,
                 "default_patience": 50,
                 "default_lr0": 0.01,
+                "two_stage": {
+                    "enabled": False,
+                    "stage1": {
+                        "epochs": 20,
+                        "lr0": 0.0005,
+                        "patience": 10,
+                        "freeze": 10,
+                    },
+                    "stage2": {
+                        "epochs": 150,
+                        "lr0": 0.0003,
+                        "patience": 30,
+                    },
+                },
             },
             "detection": {
                 "default_confidence": 0.25,
@@ -214,5 +226,5 @@ class ConfigManager:
     def get_allowed_extensions(self) -> list:
         """Get list of allowed image file extensions."""
         return self.get(
-            "image_repository.allowed_extensions", [".jpg", ".jpeg", ".png"]
+            "image_repository.allowed_extensions", Image.SUPPORTED_EXTENSIONS
         )

src/utils/file_utils.py

@@ -28,7 +28,9 @@ def get_image_files(
         List of absolute paths to image files
     """
     if allowed_extensions is None:
-        allowed_extensions = [".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp"]
+        from src.utils.image import Image
+
+        allowed_extensions = Image.SUPPORTED_EXTENSIONS
 
     # Normalize extensions to lowercase
     allowed_extensions = [ext.lower() for ext in allowed_extensions]
@@ -204,7 +206,9 @@ def is_image_file(
         True if file is an image
     """
     if allowed_extensions is None:
-        allowed_extensions = [".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp"]
+        from src.utils.image import Image
+
+        allowed_extensions = Image.SUPPORTED_EXTENSIONS
 
     extension = Path(file_path).suffix.lower()
     return extension in [ext.lower() for ext in allowed_extensions]

src/utils/image.py

@@ -277,6 +277,38 @@ class Image:
         """
         return self._channels >= 3
 
+    def convert_grayscale_to_rgb_preserve_range(
+        self,
+    ) -> PILImage.Image:
+        """Convert a single-channel PIL image to RGB while preserving dynamic range.
+
+        Returns:
+            PIL Image in RGB mode with intensities normalized to 0-255.
+        """
+        if self._channels == 3:
+            return self.pil_image
+
+        grayscale = self.data
+        if grayscale.ndim == 3:
+            grayscale = grayscale[:, :, 0]
+
+        original_dtype = grayscale.dtype
+        grayscale = grayscale.astype(np.float32)
+
+        if grayscale.size == 0:
+            return PILImage.new("RGB", self.shape, color=(0, 0, 0))
+
+        if np.issubdtype(original_dtype, np.integer):
+            denom = float(max(np.iinfo(original_dtype).max, 1))
+        else:
+            max_val = float(grayscale.max())
+            denom = max(max_val, 1.0)
+
+        grayscale = np.clip(grayscale / denom, 0.0, 1.0)
+        grayscale_u8 = (grayscale * 255.0).round().astype(np.uint8)
+        rgb_arr = np.repeat(grayscale_u8[:, :, None], 3, axis=2)
+        return PILImage.fromarray(rgb_arr, mode="RGB")
+
     def __repr__(self) -> str:
         """String representation of the Image object."""
         return (

src/utils/image_converters.py

@@ -0,0 +1,160 @@
+import numpy as np
+
+from roifile import ImagejRoi
+from tifffile import TiffFile, TiffWriter
+from pathlib import Path
+
+
+class UT:
+    """
+    Docstring for UT
+
+    Operetta files along with rois drawn in ImageJ
+    """
+
+    def __init__(self, roifile_fn: Path, no_labels: bool):
+        self.roifile_fn = roifile_fn
+        print("is file", self.roifile_fn.is_file())
+        self.rois = None
+        if no_labels:
+            self.rois = ImagejRoi.fromfile(self.roifile_fn)
+            self.stem = self.roifile_fn.stem.split("Roi-")[1]
+        else:
+            self.roifile_fn = roifile_fn / roifile_fn.parts[-1]
+            self.stem = self.roifile_fn.stem
+
+            print(self.roifile_fn)
+
+        print(self.stem)
+        self.image, self.image_props = self._load_images()
+
+    def _load_images(self):
+        """Loading sequence of tif files
+        array sequence is CZYX
+        """
+        print("Loading images:", self.roifile_fn.parent, self.stem)
+        fns = list(self.roifile_fn.parent.glob(f"{self.stem.lower()}*.tif*"))
+        stems = [fn.stem.split(self.stem)[-1] for fn in fns]
+        n_ch = len(set([stem.split("-ch")[-1].split("t")[0] for stem in stems]))
+        n_p = len(set([stem.split("-")[0] for stem in stems]))
+        n_t = len(set([stem.split("t")[1] for stem in stems]))
+
+        with TiffFile(fns[0]) as tif:
+            img = tif.asarray()
+            w, h = img.shape
+            dtype = img.dtype
+            self.image_props = {
+                "channels": n_ch,
+                "planes": n_p,
+                "tiles": n_t,
+                "width": w,
+                "height": h,
+                "dtype": dtype,
+            }
+        print("Image props", self.image_props)
+
+        image_stack = np.zeros((n_ch, n_p, w, h), dtype=dtype)
+        for fn in fns:
+            with TiffFile(fn) as tif:
+                img = tif.asarray()
+                stem = fn.stem.split(self.stem)[-1]
+                ch = int(stem.split("-ch")[-1].split("t")[0])
+                p = int(stem.split("-")[0].split("p")[1])
+                t = int(stem.split("t")[1])
+                print(fn.stem, "ch", ch, "p", p, "t", t)
+                image_stack[ch - 1, p - 1] = img
+
+        print(image_stack.shape)
+
+        return image_stack, self.image_props
+
+    @property
+    def width(self):
+        return self.image_props["width"]
+
+    @property
+    def height(self):
+        return self.image_props["height"]
+
+    @property
+    def nchannels(self):
+        return self.image_props["channels"]
+
+    @property
+    def nplanes(self):
+        return self.image_props["planes"]
+
+    def export_rois(
+        self,
+        path: Path,
+        subfolder: str = "labels",
+        class_index: int = 0,
+    ):
+        """Export rois to a file"""
+        with open(path / subfolder / f"{self.stem}.txt", "w") as f:
+            for i, roi in enumerate(self.rois):
+                rc = roi.subpixel_coordinates
+                if rc is None:
+                    print(
+                        f"No coordinates: {self.roifile_fn}, element {i}, out of {len(self.rois)}"
+                    )
+                    continue
+                xmn, ymn = rc.min(axis=0)
+                xmx, ymx = rc.max(axis=0)
+                xc = (xmn + xmx) / 2
+                yc = (ymn + ymx) / 2
+                bw = xmx - xmn
+                bh = ymx - ymn
+                coords = f"{xc/self.width} {yc/self.height} {bw/self.width} {bh/self.height} "
+                for x, y in rc:
+                    coords += f"{x/self.width} {y/self.height} "
+                f.write(f"{class_index} {coords}\n")
+
+        return
+
+    def export_image(
+        self,
+        path: Path,
+        subfolder: str = "images",
+        plane_mode: str = "max projection",
+        channel: int = 0,
+    ):
+        """Export image to a file"""
+
+        if plane_mode == "max projection":
+            self.image = np.max(self.image[channel], axis=0)
+            print(self.image.shape)
+
+        print(path / subfolder / f"{self.stem}.tif")
+        with TiffWriter(path / subfolder / f"{self.stem}.tif") as tif:
+            tif.write(self.image)
+
+
+if __name__ == "__main__":
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-i", "--input", nargs="*", type=Path)
+    parser.add_argument("-o", "--output", type=Path)
+    parser.add_argument(
+        "--no-labels",
+        action="store_false",
+        help="Source does not have labels, export only images",
+    )
+    args = parser.parse_args()
+
+    for path in args.input:
+        print("Path:", path)
+        if not args.no_labels:
+            print("No labels")
+            ut = UT(path, args.no_labels)
+            ut.export_image(args.output, plane_mode="max projection", channel=0)
+
+        else:
+            for rfn in Path(path).glob("*.zip"):
+                print("Roi FN:", rfn)
+                ut = UT(rfn, args.no_labels)
+                ut.export_rois(args.output, class_index=0)
+                ut.export_image(args.output, plane_mode="max projection", channel=0)
+
+        print()

tests/show_yolo_seg.py

@@ -0,0 +1,184 @@
+#!/usr/bin/env python3
+"""
+show_yolo_seg.py
+
+Usage:
+    python show_yolo_seg.py /path/to/image.jpg /path/to/labels.txt
+
+Supports:
+ - Segmentation polygons: "class x1 y1 x2 y2 ... xn yn"
+ - YOLO bbox lines as fallback: "class x_center y_center width height"
+Coordinates can be normalized [0..1] or absolute pixels (auto-detected).
+"""
+import sys
+import cv2
+import numpy as np
+import matplotlib.pyplot as plt
+import argparse
+from pathlib import Path
+import random
+
+
+def parse_label_line(line):
+    parts = line.strip().split()
+    if not parts:
+        return None
+    cls = int(float(parts[0]))
+    coords = [float(x) for x in parts[1:]]
+    return cls, coords
+
+
+def coords_are_normalized(coords):
+    # If every coordinate is between 0 and 1 (inclusive-ish), assume normalized
+    if not coords:
+        return False
+    return max(coords) <= 1.001
+
+
+def yolo_bbox_to_xyxy(coords, img_w, img_h):
+    # coords: [xc, yc, w, h] normalized or absolute
+    xc, yc, w, h = coords[:4]
+    if max(coords) <= 1.001:
+        xc *= img_w
+        yc *= img_h
+        w *= img_w
+        h *= img_h
+    x1 = int(round(xc - w / 2))
+    y1 = int(round(yc - h / 2))
+    x2 = int(round(xc + w / 2))
+    y2 = int(round(yc + h / 2))
+    return x1, y1, x2, y2
+
+
+def poly_to_pts(coords, img_w, img_h):
+    # coords: [x1 y1 x2 y2 ...] either normalized or absolute
+    if coords_are_normalized(coords[4:]):
+        coords = [
+            coords[i] * (img_w if i % 2 == 0 else img_h) for i in range(len(coords))
+        ]
+    pts = np.array(coords, dtype=np.int32).reshape(-1, 2)
+    return pts
+
+
+def random_color_for_class(cls):
+    random.seed(cls)  # deterministic per class
+    return tuple(int(x) for x in np.array([random.randint(0, 255) for _ in range(3)]))
+
+
+def draw_annotations(img, labels, alpha=0.4, draw_bbox_for_poly=True):
+    # img: BGR numpy array
+    overlay = img.copy()
+    h, w = img.shape[:2]
+    for cls, coords in labels:
+        if not coords:
+            continue
+        # polygon case (>=6 coordinates)
+        if len(coords) >= 6:
+            color = random_color_for_class(cls)
+
+            x1, y1, x2, y2 = yolo_bbox_to_xyxy(coords[:4], w, h)
+            cv2.rectangle(img, (x1, y1), (x2, y2), color, 2)
+
+            pts = poly_to_pts(coords[4:], w, h)
+            # fill on overlay
+            cv2.fillPoly(overlay, [pts], color)
+            # outline on base image
+            cv2.polylines(img, [pts], isClosed=True, color=color, thickness=2)
+            # put class text at first point
+            x, y = int(pts[0, 0]), int(pts[0, 1]) - 6
+            cv2.putText(
+                img,
+                str(cls),
+                (x, max(6, y)),
+                cv2.FONT_HERSHEY_SIMPLEX,
+                0.6,
+                (255, 255, 255),
+                2,
+                cv2.LINE_AA,
+            )
+
+        # YOLO bbox case (4 coords)
+        elif len(coords) == 4:
+            x1, y1, x2, y2 = yolo_bbox_to_xyxy(coords, w, h)
+            color = random_color_for_class(cls)
+            cv2.rectangle(img, (x1, y1), (x2, y2), color, 2)
+            cv2.putText(
+                img,
+                str(cls),
+                (x1, max(6, y1 - 4)),
+                cv2.FONT_HERSHEY_SIMPLEX,
+                0.6,
+                (255, 255, 255),
+                2,
+                cv2.LINE_AA,
+            )
+        else:
+            # Unknown / invalid format, skip
+            continue
+
+    # blend overlay for filled polygons
+    cv2.addWeighted(overlay, alpha, img, 1 - alpha, 0, img)
+    return img
+
+
+def load_labels_file(label_path):
+    labels = []
+    with open(label_path, "r") as f:
+        for raw in f:
+            line = raw.strip()
+            if not line:
+                continue
+            parsed = parse_label_line(line)
+            if parsed:
+                labels.append(parsed)
+    return labels
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Show YOLO segmentation / polygon annotations"
+    )
+    parser.add_argument("image", type=str, help="Path to image file")
+    parser.add_argument("labels", type=str, help="Path to YOLO label file (polygons)")
+    parser.add_argument(
+        "--alpha", type=float, default=0.4, help="Polygon fill alpha (0..1)"
+    )
+    parser.add_argument(
+        "--no-bbox", action="store_true", help="Don't draw bounding boxes for polygons"
+    )
+    args = parser.parse_args()
+
+    img_path = Path(args.image)
+    lbl_path = Path(args.labels)
+
+    if not img_path.exists():
+        print("Image not found:", img_path)
+        sys.exit(1)
+    if not lbl_path.exists():
+        print("Label file not found:", lbl_path)
+        sys.exit(1)
+
+    img = cv2.imread(str(img_path), cv2.IMREAD_COLOR)
+    if img is None:
+        print("Could not load image:", img_path)
+        sys.exit(1)
+
+    labels = load_labels_file(str(lbl_path))
+    if not labels:
+        print("No labels parsed from", lbl_path)
+        # continue and just show image
+    out = draw_annotations(
+        img.copy(), labels, alpha=args.alpha, draw_bbox_for_poly=(not args.no_bbox)
+    )
+
+    # Convert BGR -> RGB for matplotlib display
+    out_rgb = cv2.cvtColor(out, cv2.COLOR_BGR2RGB)
+    plt.figure(figsize=(10, 10 * out.shape[0] / out.shape[1]))
+    plt.imshow(out_rgb)
+    plt.axis("off")
+    plt.title(f"{img_path.name} ({lbl_path.name})")
+    plt.show()
+
+
+if __name__ == "__main__":
+    main()

tests/test_image.py

@@ -27,7 +27,7 @@ class TestImage:
 
     def test_supported_extensions(self):
         """Test that supported extensions are correctly defined."""
-        expected_extensions = [".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp"]
+        expected_extensions = Image.SUPPORTED_EXTENSIONS
         assert Image.SUPPORTED_EXTENSIONS == expected_extensions
 
     def test_image_properties(self, tmp_path):