histolab skill
Lightweight WSI tile extraction and preprocessing. Use for basic slide processing, tissue detection, tile extraction, and stain normalization for H&E images. Best for simple pipelines, dataset preparation, and quick tile-based analysis. For advanced spatial proteomics, multiplexed imaging, or deep learning pipelines use pathml.
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Install the histolab skill
A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description.
git clone --depth 1 https://github.com/K-Dense-AI/scientific-agent-skills.git /tmp/scientific-agent-skills mkdir -p ~/.claude/skills cp -r /tmp/scientific-agent-skills/skills/histolab ~/.claude/skills/histolab
In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub
The instructions your agent would load
SKILL.md as published, without the frontmatter. Read it on GitHub
Histolab
Overview
Histolab is a Python library for processing whole slide images (WSI) in digital pathology. It automates tissue detection, extracts informative tiles from gigapixel images, and prepares datasets for deep learning pipelines. The library handles multiple WSI formats, implements sophisticated tissue segmentation, and provides flexible tile extraction strategies.
Installation
Install OpenSlide system libraries first (OpenSlide download), then install histolab:
uv pip install histolabFor built-in TCGA sample slides via histolab.data, also install pooch:
uv pip install poochHistolab 0.7.0 (latest stable) supports Python 3.8–3.11 on Linux and macOS. Windows is not supported as of 0.7.0.
Quick Start
Basic workflow for extracting tiles from a whole slide image:
from histolab.slide import Slide
from histolab.tiler import RandomTiler
# Load slide
slide = Slide("slide.svs", processed_path="output/")
# Configure tiler
tiler = RandomTiler(
tile_size=(512, 512),
n_tiles=100,
level=0,
seed=42
)
# Preview tile locations
tiler.locate_tiles(slide, n_tiles=20)
# Extract tiles
tiler.extract(slide)Core Capabilities
Six capability areas, each with worked code, are documented in references/core_capabilities.md:
tissue-fraction control.
- Slide management — opening slides, properties, levels, thumbnails, and scaled images.
- Tissue detection and masks — TissueMask and BiggestTissueBoxMask, and custom masks.
- Tile extraction — random, grid, and score-based tilers with size, level, and
- Filters and preprocessing — image and morphological filters, and composing them.
- Stain normalization — Reinhard and Macenko normalization against a target image.
- Visualization — locating tiles on the slide and inspecting masks and extractions.
Five end-to-end workflows are in references/typicalworkflows.md. Per-topic detail lives in references/slidemanagement.md, references/tissuemasks.md, references/tileextraction.md, references/filters_preprocessing.md, and references/visualization.md.
Best Practices
Slide Loading and Inspection
- Always inspect slide properties before processing
- Save thumbnails with slide.thumbnail.save() for quick visual review
- Check pyramid levels and dimensions
- Verify tissue is present using thumbnails
Tissue Detection
- Preview masks with locate_mask() before extraction
- Use TissueMask for multiple sections, BiggestTissueBoxMask for single sections
- Customize filters for specific stains (H&E vs IHC)
- Handle pen annotations with custom masks
- Test masks on diverse slides
Tile Extraction
- Always preview with locatetiles() before extracting**
- Choose appropriate tiler:
- RandomTiler: Sampling and exploration
- GridTiler: Complete coverage
- ScoreTiler: Quality-driven selection
- Set appropriate tissue_percent threshold (70-90% typical)
- Use seeds for reproducibility in RandomTiler
- Extract at appropriate pyramid level for analysis resolution
- Enable logging for large datasets
Performance
- Extract at lower levels (1, 2) for faster processing
- Use BiggestTissueBoxMask over TissueMask when appropriate
- Adjust tissue_percent to reduce invalid tile attempts
- Limit n_tiles for initial exploration
- Use pixel_overlap=0 for non-overlapping grids
Quality Control
- Validate tile quality (check for blur, artifacts, focus)
- Review score distributions for ScoreTiler
- Inspect top and bottom scoring tiles
- Monitor tissue coverage statistics
- Filter extracted tiles by additional quality metrics if needed
Common Use Cases
Training Deep Learning Models
- Extract balanced datasets using RandomTiler across multiple slides
- Use ScoreTiler with NucleiScorer to focus on cell-rich regions
- Extract at consistent resolution (level 0 or level 1)
- Generate CSV reports for tracking tile metadata
Whole Slide Analysis
- Use GridTiler for complete tissue coverage
- Extract at multiple pyramid levels for hierarchical analysis
- Maintain spatial relationships with grid positions
- Use pixel_overlap for sliding window approaches
Tissue Characterization
- Sample diverse regions with RandomTiler
- Quantify tissue coverage with masks
- Extract stain-specific information with HED decomposition
- Compare tissue patterns across slides
Quality Assessment
- Identify optimal focus regions with ScoreTiler
- Detect artifacts using custom masks and filters
- Assess staining quality across slide collection
- Flag problematic slides for manual review
Dataset Curation
- Use ScoreTiler to prioritize informative tiles
- Filter tiles by tissue percentage
- Generate reports with tile scores and metadata
- Create stratified datasets across slides and tissue types
Troubleshooting
No tiles extracted
- Lower tissue_percent threshold
- Verify slide contains tissue (check thumbnail)
- Ensure extraction_mask captures tissue regions
- Check tile_size is appropriate for slide resolution
Many background tiles
- Enable check_tissue=True
- Increase tissue_percent threshold
- Use appropriate mask (TissueMask vs BiggestTissueBoxMask)
- Customize mask filters to better detect tissue
Extraction very slow
- Extract at lower pyramid level (level=1 or 2)
- Reduce n_tiles for RandomTiler/ScoreTiler
- Use RandomTiler instead of GridTiler for sampling
- Use BiggestTissueBoxMask instead of TissueMask
Tiles have artifacts
- Implement custom annotation-exclusion masks
- Adjust filter parameters for artifact removal
- Increase small object removal threshold
- Apply post-extraction quality filtering
Inconsistent results across slides
- Use same seed for RandomTiler
- Normalize staining with MacenkoStainNormalizer or ReinhardStainNormalizer
- Adjust tissue_percent per staining quality
- Implement slide-specific mask customization
Resources
This skill includes detailed reference documentation in the references/ directory:
references/slide_management.md
Comprehensive guide to loading, inspecting, and working with whole slide images:
- Slide initialization and configuration
- Built-in sample datasets
- Slide properties and metadata
- Thumbnail generation and visualization
- Working with pyramid levels
- Multi-slide processing workflows
- Best practices and common patterns
references/tissue_masks.md
Complete documentation on tissue detection and masking:
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