ComfyUI-SDMatte

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ComfyUI custom nodes plugin based on SDMatte for interactive image matting.

🚀 Quick Start

📺 Video Tutorial: ComfyUI-SDMatte Tutorial
🔧 Example Workflow: Superior Image Cropping and Mask Refinement Workflow
💡 Recommended: Watch the video tutorial first to understand the usage, then download the workflow for practice

📖 Introduction

SDMatte is an interactive image matting method based on Stable Diffusion, developed by the vivo Camera Research team and accepted by ICCV 2025. This method leverages the powerful priors of pre-trained diffusion models and supports multiple visual prompts (points, boxes, masks) for accurately extracting target objects from natural images.

This plugin integrates SDMatte into ComfyUI, providing a simple and easy-to-use node interface focused on trimap-guided matting functionality with built-in VRAM optimization strategies.

🖼️ Examples

Matting Results

<table> <tr> <td align="center"><strong>Original Image</strong></td> <td align="center"><strong>Trimap</strong></td> <td align="center"><strong>Matting Result</strong></td> </tr> <tr> <td><img src="example_workflow/test_1.png" width="200"/></td> <td><img src="example_workflow/test_2.png" width="200"/></td> <td><em>Alpha mask output</em></td> </tr> </table>

Example workflow demonstrating SDMatte's high-precision matting capabilities with trimap guidance.

✨ Features

• 🎯 High-Precision Matting: Based on powerful diffusion model priors, capable of handling complex edge details
• 🖼️ Trimap Guidance: Supports trimap-guided precise matting
• 🚀 VRAM Optimization: Built-in mixed precision, attention slicing, and other memory optimization strategies
• 🔧 ComfyUI Integration: Fully compatible with ComfyUI workflow system
• 📥 Automatic Model Download: Automatically downloads model weights on first use
• 📱 Flexible Sizes: Supports multiple inference resolutions (512-1024px)

🛠️ Installation

1. Download Plugin

Place this plugin in the ComfyUI custom nodes directory:

cd ComfyUI/custom_nodes/
git clone https://github.com/flybirdxx/ComfyUI-SDMatte.git

2. Install Dependencies

ComfyUI will automatically install the dependencies in requirements.txt on startup:

• diffusers
• timm
• einops
• lazyconfig

3. Automatic Model Download

No manual download is required.

The first time you use the Apply SDMatte node, it will automatically check for and download the necessary model weights from Hugging Face. The models will be stored in: ComfyUI/models/SDMatte/

You can select between the standard (SDMatte.pth) and enhanced (SDMatte_plus.pth) versions directly within the node.

4. Restart ComfyUI

Restart ComfyUI to load the new custom nodes.

🎮 Usage

Node Description

Apply SDMatte

• Function: Loads the model and applies it for matting in a single node.
• Input:
  • ckpt_name: Select the model to use (SDMatte.pth or SDMatte_plus.pth). It will be downloaded automatically if not found.
  • image: Input image (ComfyUI IMAGE format)
  • trimap: Trimap mask (ComfyUI MASK format)
  • inference_size: Inference resolution (512/640/768/896/1024)
  • is_transparent: Whether the image contains transparent areas
  • output_mode: Output mode (alpha_only, matted_rgba, matted_rgb)
  • mask_refine: Enable mask refinement to reduce background interference
  • trimap_constraint: Strength of the trimap constraint for refinement
  • force_cpu: Force CPU inference (optional)
• Output:
  • alpha_mask: Alpha mask of the matting result
  • matted_image: The matted image result

Basic Workflow

1. Load Image: Load the image that needs matting
2. Create Trimap: Use drawing tools or other nodes to create trimap
   • Black (0): Definite background
   • White (1): Definite foreground
   • Gray (0.5): Unknown region
3. Apply SDMatte: Apply matting
4. Preview Image: Preview matting result

Recommended Settings

• Inference Resolution: 1024 (highest quality) or 768 (balanced performance)
• Transparent Flag: Set according to whether input image has transparent channel
• Force CPU: Use only when GPU VRAM is insufficient

🔧 Technical Details

Data Processing

• Input Image: Automatically resized to inference resolution, normalized to [-1, 1]
• Trimap: Resized to inference resolution, mapped to [-1, 1] range
• Output: Resized back to original resolution, clamped to [0, 1] range

VRAM Optimization

The plugin has built-in memory optimization strategies (automatically enabled):

• Mixed Precision: Uses FP16 autocast to reduce VRAM usage
• Attention Slicing: SlicedAttnProcessor(slice_size=1) maximizes VRAM savings
• Memory Cleanup: Automatically clears CUDA cache before and after inference
• Device Management: Smart device allocation and model movement

Model Loading

• Weight Formats: Supports .pth and .safetensors formats
• Safe Loading: Handles omegaconf objects, supports weights_only mode
• Nested Structure: Automatically handles complex checkpoint structures
• Error Recovery: Multiple fallback mechanisms ensure successful loading

❓ FAQ

Q: Nodes cannot be searched?

A: Ensure the plugin directory structure is correct, restart ComfyUI, check console for error messages.

Q: Model loading failed?

A: Check SDMatte.pth file path, ensure base model directory structure is complete, view console for detailed error messages.

Q: Insufficient VRAM during inference?

A: Try reducing inference resolution, enable force_cpu option, or close other VRAM-consuming programs.

Q: Poor matting results?

A: Optimize trimap quality, ensure accurate foreground/background/unknown region annotations, try different inference resolutions.

Q: First inference is slow?

A: First run needs to compile CUDA kernels, subsequent inference will be significantly faster.

Q: Which model version should I choose?

A:

• SDMatte.pth (Standard): Smaller file (~11GB), faster inference, suitable for most scenarios
• SDMatte_plus.pth (Enhanced): Larger file, higher accuracy, suitable for professional use with extremely high quality requirements
• Recommend testing with standard version first, upgrade to enhanced version if higher quality is needed

📋 System Requirements

• ComfyUI: Latest version
• Python: 3.8+
• PyTorch: 1.12+ (CUDA support recommended)
• VRAM: 8GB+ recommended (CPU inference supported)
• Dependencies: diffusers, timm, einops, lazyconfig

📝 Changelog

v1.3.0 (2025-08-17)

• ✨ New Features:
  • Implemented automatic model downloading and checking. Models are now stored in ComfyUI/models/SDMatte/.
• 🔧 Improvements:
  • Merged SDMatte Model Loader and SDMatte Apply nodes into a single Apply SDMatte node for a more streamlined workflow.
  • Refactored code for better stability.

v1.2.0 (2025-08-15)

• ✨ New Features:
  • Added image output alongside alpha mask output
  • Support for transparent background matting mode
  • Added multiple output modes: alpha_only, matted_rgba, matted_rgb
  • Added mask refinement feature using trimap constraints to filter unwanted regions
  • Added trimap_constraint parameter to control constraint strength
  • Added detailed tooltips for all parameters
• 🔧 Improvements:
  • Improved alpha mask processing logic to reduce background interference
  • Optimized foreground region extraction algorithm
  • Enhanced low-confidence region filtering mechanism
• 📚 Documentation:
  • Added example workflow links
  • Added video tutorial links
  • Improved usage instructions and parameter explanations
• 🔧 Improvements:
  • Improved VRAM optimization strategies
  • Enhanced model loading stability
  • Optimized inference performance

v1.0.0 (2025-08-14)

• 🎉 Initial Release:
  • Basic SDMatte model integration
  • Support for trimap-guided matting
  • Built-in VRAM optimization features
  • Support for multiple inference resolutions

📚 References

• Example Workflow: Superior Image Cropping and Mask Refinement Workflow
• Video Tutorial: ComfyUI-SDMatte Tutorial
• Original Paper: SDMatte: Grafting Diffusion Models for Interactive Matting (ICCV 2025)
• Original Code: vivoCameraResearch/SDMatte
• Model Weights: LongfeiHuang/SDMatte

📄 License

This project follows the MIT license. The original SDMatte project also uses the MIT license.

🙏 Acknowledgements

Thanks to the vivo Camera Research team for developing the excellent SDMatte model, and to the Stable Diffusion and ComfyUI communities for their contributions.

📧 Support

If you have any questions or suggestions, please submit an Issue on GitHub.

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Note: This plugin is a third-party implementation and is not directly affiliated with the original SDMatte team. Please ensure compliance with relevant license terms before use.