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Mask Auto-Label

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Efficiently generate segmentation masks with minimal annotations.

by nvidia2.8k stars on nvidia/skills
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Updated Aug 7, 2026
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Free · Opens the source repo

What Mask Auto-Label does

Mask Auto-Label (MAL) is a tool designed for weakly-supervised segmentation tasks, allowing users to produce segmentation masks from minimal annotations, such as point or box annotations. This skill leverages a Vision Transformer (ViT) backbone, specifically the ViT-MAE variant, to enhance the efficiency of the segmentation process. By utilizing MAL, developers and data scientists can streamline their workflows, particularly when working with datasets that have limited labeled data.

The skill is particularly useful in scenarios where traditional segmentation methods require extensive manual labeling, which can be time-consuming and labor-intensive. With MAL, users can initiate training, evaluation, or inference processes for their segmentation models with ease. The skill is designed to be integrated into existing workflows, allowing for seamless transitions between training and evaluation phases while maintaining flexibility in dataset management.

MAL's architecture is built around AutoML capabilities, enabling users to optimize their training processes automatically. This feature is particularly beneficial for users who may not have deep expertise in hyperparameter tuning, as the skill can handle these complexities in the background. The model requires specific dataset formats and configurations, which are clearly outlined in the provided schemas and documentation, ensuring that users can set up their environments effectively.

Overall, Mask Auto-Label is an essential tool for developers and researchers in the field of computer vision, particularly those focused on segmentation tasks. Its ability to work with minimal annotations and its integration with AutoML features make it a valuable addition to any machine learning toolkit.

When to use it

Use this skill when you need to generate segmentation masks from limited labeled data, especially in weakly-supervised scenarios.

When not to use it

This skill is not suitable for tasks that require fully supervised segmentation with extensive annotations or for datasets that do not conform to the required formats.

What you can build with it

Generating Masks from Minimal Annotations

Use MAL to create segmentation masks from point or box annotations, significantly reducing the labeling effort.

Integrating with AutoML Workflows

Leverage MAL's AutoML capabilities to automate hyperparameter tuning during model training.

Evaluating Segmentation Models

Utilize MAL to evaluate the performance of segmentation models with minimal setup, focusing on efficiency.

How to install Mask Auto-Label

View source

1. Install with the skills CLI

npx skills add nvidia/skills/tao-train-mask-auto-label --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by nvidia

MAL

MAL (Mask Auto-Label) for weakly-supervised segmentation. Produces segmentation masks from minimal annotations (e.g., point or box annotations). Uses ViT-MAE backbone.

Set train.pretrained_model_path for ViT-MAE pretrained weights.

Dataclass Schemas

Generated TAO Core schemas are packaged in schemas/<action>.schema.json, with schemas/manifest.json listing available actions. Each generated schema also emits references/spec_template_<action>.yaml from the schema top-level default field. AutoML enablement is declared at the model layer in references/skill_info.yaml via automl_enabled. Runnable AutoML still requires schemas/train.schema.json and references/spec_template_train.yaml to exist and parse. Use the packaged train schema for automl_default_parameters, automl_disabled_parameters, defaults, min/max bounds, enums, option weights, math conditions, dependencies, and popular parameters. Do not expect ~/tao-core at runtime; maintainers regenerate schemas/templates before packaging the skill bank.

Train Action Policy

This model is AutoML-enabled at the model layer. Before handling any train-stage request, read references/skill_info.yaml and resolve the run override from either an explicit automl_policy value or the user's workflow request. Use automl_policy: on by default and only expose on / off in new launch prompts. Treat phrases like "turn off AutoML", "disable AutoML", "no HPO", or "plain training" as automl_policy: off for this run only. When automl_policy: on, automl_enabled: true, and both schemas/train.schema.json and references/spec_template_train.yaml are packaged, route the train action through tao-skill-bank:tao-run-automl by default with this model's skill_dir. Preserve workflow/application overrides for datasets, specs, output directories, GPU/platform settings, parent checkpoints, and automl_policy. Use direct model training only when automl_policy: off or the packaged train schema/template is missing; in the missing-schema case, report that AutoML is enabled but not runnable for this model until schemas are generated.

Non-train actions such as evaluate, inference, export, and deploy flows stay in this model skill. The per-run automl_policy override does not change model metadata.

Training Requirements

  • Dataset type: segmentation
  • Formats: default
  • Monitoring metric: mIoU

Per-Action Dataset Requirements

ActionSpec KeySourceFilesList?
evaluatedataset.val_img_direval_datasetimages.tar.gzNo
evaluatedataset.val_ann_patheval_datasetannotations.jsonNo
inferenceinference.img_dirinference_datasetimages.tar.gzNo
inferenceinference.ann_pathinference_datasetannotations.jsonNo
traindataset.train_img_dirtrain_datasetsimages.tar.gzNo
traindataset.train_ann_pathtrain_datasetsannotations.jsonNo
traindataset.val_img_direval_datasetimages.tar.gzNo
traindataset.val_ann_patheval_datasetannotations.jsonNo

Typical Spec Overrides

Data source overrides are mandatory for every action — the agent MUST construct data source paths from the Per-Action Dataset Requirements table above and include them in spec_overrides. MAL expects COCO-style annotation JSON plus image paths that match the JSON file_name entries after the data source is prepared. Archive-only CSV/image datasets are not compatible unless they are converted to this format first.

S3_TRAIN = "s3://bucket/data/train"
S3_EVAL = "s3://bucket/data/eval"

train (mandatory data sources):

{
    "train.num_gpus": 1,
    "train.gpu_ids": [
        0
    ],
    "train.num_epochs": 5,
    "train.checkpoint_interval": 5,
    "train.validation_interval": 5,
    "dataset.train_img_dir": f"{S3_TRAIN}/images.tar.gz",
    "dataset.train_ann_path": f"{S3_TRAIN}/annotations.json",
    "dataset.val_img_dir": f"{S3_EVAL}/images.tar.gz",
    "dataset.val_ann_path": f"{S3_EVAL}/annotations.json",
}

evaluate (mandatory data sources):

{
    "evaluate.checkpoint": "<selected train/AutoML checkpoint>",
    "dataset.val_img_dir": f"{S3_EVAL}/images.tar.gz",
    "dataset.val_ann_path": f"{S3_EVAL}/annotations.json",
}

inference (mandatory data sources):

{
    "inference.checkpoint": "<selected train/AutoML checkpoint>",
    "inference.img_dir": f"{S3_EVAL}/images.tar.gz",
    "inference.ann_path": f"{S3_EVAL}/annotations.json",
}

For checkpoint-dependent actions, use the model resolver declared in references/skill_info.yaml. Select the exact epoch/step checkpoint requested by the user or the best checkpoint when a best-checkpoint action is requested. The mal_model_latest.pth symlink is only appropriate when the user explicitly asks for the latest checkpoint.

Eval Dataset

Optional. Val images and annotations configured alongside train paths.

Important Parameters

  • model.arch: ViT-MAE backbone variant. Default vit-mae-base/16. Avoid vit-deit-tiny/16; the current runtime rejects tiny ViT variants.
  • train.lr: Learning rate. Default 1e-6 (very low — fine-tuning ViT).
  • dataset.crop_size: Training crop size. Default 512. Use this key, not model.crop_size.
  • train.warmup_epochs: Warmup epochs before full learning rate.
  • model.load_mask: Whether to load pre-computed masks.

AutoML / HPO Notes

For MAL AutoML launches, keep the default smoke search space narrow and pass automl_hyperparameters=["train.lr", "train.wd"]. Use conservative Bayesian ranges around the ViT-MAE fine-tuning defaults, for example train.lr from 1e-7 to 1e-5 and train.wd from 1e-5 to 1e-2. The packaged train schema marks these two parameters as the default AutoML parameters; pass them explicitly when using a runtime that still derives MAL search metadata from its bundled config module.

Multi-GPU / Multi-Node

Launch method: Lightning-managed (single python process, Lightning spawns workers).

Spec KeyDescriptionDefault
train.num_gpusNumber of GPUs1
train.gpu_idsGPU device indices[0]
train.num_nodesNumber of nodes1
  • Multi-GPU strategy: ddp_find_unused_parameters_true
  • No fsdp support
  • LR auto-scaling: lr = lr * num_devices * batch_size (learning rate is scaled automatically by device count and batch size)

Multi-node env vars (set by orchestrator): WORLD_SIZE, NODE_RANK, MASTER_ADDR, MASTER_PORT, NUM_GPU_PER_NODE.

Hardware

Minimum 1 GPU(s), recommended 2 GPU(s). 24GB+ (A100 recommended) VRAM per GPU. ViT-MAE backbone at crop_size=512 needs 24GB+ GPU memory.

Error Patterns

CUDA out of memory: Reduce dataset.crop_size (512 -> 384 -> 256) or use a smaller ViT-MAE variant (base vs large).

Key crop_size not in MALModelConfig: The crop-size override was placed under model.crop_size. Move it to dataset.crop_size.

Spec Param / Parent Model Inference

Model-specific inference mappings belong in this MD file, not in config.json. Generated runners should read this section and apply the mappings with SDK helpers before create_job(). This mirrors the old microservices infer_params.py flow.

Inference mappings from TAO Core mal.config.json:

ActionSpec FieldInference FunctionMeaning
evaluateevaluate.checkpointparent_modelmodel file inferred from the parent job results folder
evaluateresults_diroutput_dircurrent job results directory
inferenceinference.checkpointparent_modelmodel file inferred from the parent job results folder
inferenceinference.label_dump_pathcreate_inference_result_file_malMAL inference JSON path
inferenceresults_diroutput_dircurrent job results directory
traintrain.pretrained_model_pathptm_if_no_resume_modeloptional pretrained model when not resuming
traintrain.resume_training_checkpoint_pathresume_modelexact checkpoint for resume runs
trainresults_diroutput_dircurrent job results directory

For parent_model or parent_model_folder, pass the upstream train/export/AutoML child job id as parent_job_id. The SDK lists the parent result folder, filters checkpoint artifacts, and returns the selected model file or folder. Do not add these mappings back to config.json and do not patch generated runner scripts to guess checkpoint paths.

Frequently asked questions about Mask Auto-Label

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