labelimgplusplus 3.0.0

Core Annotation Features

• Five annotation formats: PASCAL VOC, YOLO bbox, CreateML, COCO, and YOLO-seg

• Bounding box and polygon annotation with interactive editing

• Keypoint annotation with COCO 17-point human pose and 5-point face templates; COCO preserves keypoints on export

• Auto-save mode for uninterrupted workflow

• Predefined class labels with customizable list

• Verification system to mark completed annotations

Workflow and Interface

Undo/Redo Support

Full undo/redo for annotation actions. Press Ctrl+Z to undo and Ctrl+Shift+Z to redo.

Gallery Mode with Annotation Preview

Visual thumbnail gallery showing all images with bounding box and polygon overlays directly on thumbnails across all five annotation formats.

• Colored borders indicate status: Gray (no labels), Blue (has labels), Green (verified)

• Bounding boxes use compact corner markers; polygons use outline previews

• Quick size presets (S/M/L/XL) plus slider for fine control

• Smart selection: click on nested boxes selects the inner box

• Press Ctrl+G to toggle gallery mode

Modern UI with Feather Icons

Clean, modern interface with beautiful Feather icons and improved visual design.

Responsive DPI Scaling

Icons and UI elements scale properly on high-DPI displays (4K, Retina).

Expandable Toolbar

Click the chevron at the bottom of the toolbar to expand/collapse and show full button labels.

Consolidated File Menu

Open File, Open Dir, and Change Save Dir combined into a single dropdown for cleaner toolbar.

Brightness Adjustment

Adjust image brightness on-the-fly to better see annotations on dark or light images.

Dark Mode Theme

Choose between light and dark themes for comfortable annotation in any lighting condition.

• Press Ctrl+Shift+T to toggle between themes

• Theme preference automatically saved

• All UI components (canvas, gallery, dialogs) respect the active theme

• See Dark Mode Documentation for detailed information

SAM-Assisted Segmentation (optional)

Click once on an object to auto-generate a polygon, traced from a Segment-Anything mask. Install the optional extra and toggle SAM Segment:

pip install labelimgplusplus[sam]

Runs the lightweight MobileSAM model on ONNX Runtime as a CPU-friendly extra with no PyTorch dependency. The default model pair is downloaded and checksum-verified on first use. Point Tools → SAM Settings… at your own exported encoder/decoder pair to use a different SAM variant. Without the extra installed, the action stays disabled (with an install hint) and nothing else changes.

From PyPI (Recommended)

Note: The command was renamed from labelImgPlusPlus to labelimgpp in v2.1.1. The old command still works but shows a deprecation warning.

pip3 install labelimgplusplus
labelimgpp

Or use the full command name:

labelimgplusplus

With a specific image or directory:

labelimgpp [IMAGE_PATH] [PRE-DEFINED CLASS FILE] [SAVE_DIR]

Build from Source

Ubuntu/Linux:

sudo apt-get install pyqt5-dev-tools
pip3 install -r requirements/requirements-linux-python3.txt
make qt5py3
python3 labelImgPlusPlus.py

macOS:

pip3 install pyqt5 lxml
make qt5py3
python3 labelImgPlusPlus.py

Windows:

pip install pyqt5 lxml
pyrcc5 -o libs/resources.py resources.qrc
python labelImgPlusPlus.py