ComfyUI Extension: Luminance Stack Processor

Luminance-Stack-Processor Introduction

The Luminance-Stack-Processor is an innovative extension designed to enhance the capabilities of ComfyUI by providing advanced High Dynamic Range (HDR) processing nodes. This extension is particularly beneficial for AI artists who work with both AI-generated and real-world images. It introduces custom HDR processing methods, such as the Detail Injection algorithm and the Radiance Fusion Algorithm, which are tailored to improve image quality by preserving details across various exposure levels. By using this extension, you can achieve professional-grade HDR outputs, making it an essential tool for artists looking to enhance their creative workflows.

How Luminance-Stack-Processor Works

At its core, the Luminance-Stack-Processor works by taking multiple images with different exposure levels and combining them into a single HDR image. This process involves several steps:

1. Exposure Stacking: The extension takes multiple images captured at different exposure levels (e.g., overexposed, underexposed) and aligns them to ensure consistency.
2. Detail Injection: This algorithm intelligently injects details from underexposed and overexposed images into the base image, enhancing both highlights and shadows.
3. Radiance Fusion: Inspired by VFX pipeline operations, this method blends exposures using mathematical operations to maintain a natural appearance while preserving dynamic range.
4. HDR Output: The final result is a true HDR image with values that exceed the standard 0-1 range, suitable for professional editing and compositing workflows.

Luminance-Stack-Processor Features

• Detail Injection Algorithm: Automatically detects and corrects gamma encoding, performs linear conversion, and recovers details in highlights and shadows.
• Radiance Fusion Algorithm: Offers an alternative HDR processing method with a focus on maintaining a natural look.
• True 32-bit EXR Export: Ensures professional bit-depth control for high-quality image exports.
• Adaptive Calibration: Analyzes and corrects exposure relationships for AI-generated images, ensuring accurate HDR reconstruction.
• Custom Nodes: Includes nodes for processing 3-stop and 5-stop exposure stacks, as well as a latent stack processor for faster processing in latent space.

Luminance-Stack-Processor Models

The extension includes several models and algorithms, each suited for different scenarios:

• Detail Injection: Best for AI-generated images, providing a natural appearance with automatic brightness compensation.
• Radiance Fusion: Ideal for VFX workflows, offering a display-ready output with good dynamic range.
• Debevec with Adaptive Calibration: Suitable for VFX compositing, providing scene-referred linear data.
• Robertson with Adaptive Calibration: An alternative to Debevec, offering similar features.
• Mertens and Natural Blend: Legacy algorithms under development for traditional exposure fusion.

Troubleshooting Luminance-Stack-Processor

Common Issues and Solutions

1. Module Not Found Error: Ensure all dependencies are installed using pip install -r requirements.txt and restart ComfyUI.
2. Color Accuracy Problems: Use the Radiance Fusion algorithm for the best color accuracy.
3. Poor HDR Results: Verify that input images are properly exposed and aligned. Use a tripod for traditional captures.
4. Memory Issues: Process smaller images first and ensure adequate RAM is available.

Frequently Asked Questions

• Why do my images look flat and desaturated? This is expected for VFX workflows, as it preserves raw linear radiance data. Apply viewing LUTs in post-processing software for proper display.
• Can I use this extension with AI-generated images? Yes, the adaptive calibration system is designed to handle non-physical exposure relationships in AI-generated images.

Learn More about Luminance-Stack-Processor

For further learning and support, consider exploring the following resources:

• ComfyUI Documentation: ComfyUI Custom Node Guidelines
• HDR Processing Tutorials: Explore online tutorials on HDR processing to understand the principles and techniques used in this extension.
• Community Forums: Join discussions on platforms like GitHub Discussions or Discord to connect with other AI artists and developers using the Luminance-Stack-Processor. By leveraging these resources, you can enhance your understanding and make the most of the Luminance-Stack-Processor in your creative projects.