ComfyUI-Kontext-API

A custom ComfyUI node for integrating with the Fal Kontext API for advanced image editing and generation.

Features

• Image-to-Image Generation: Transform images based on text prompts using Fal's Kontext model
• Single Image Output: Generates one image per request for optimal ComfyUI compatibility
• Seed Control: Use specific seeds for reproducible results or -1 for random
• Prompt Enhancement: Optional AI prompt enhancement (can be disabled)

Installation

1. Clone this repository into your ComfyUI custom nodes directory:

cd ComfyUI/custom_nodes
git clone https://github.com/SanDiegoDude/ComfyUI-Kontext-API.git

2. Install required dependencies:

cd ComfyUI-Kontext-API
pip install -r requirements.txt

3. Set up your Fal API key (REQUIRED):

Getting a Fal API Key

1. Sign up at https://fal.ai/
2. Go to your dashboard
3. Generate an API key

Setting up the API Key

Choose one of these methods:

Option 1: Create a .fal_key file (Recommended)

1. Create a file named .fal_key in the ComfyUI-Kontext-API directory
2. Put your Fal API key in this file (just the key, nothing else)
3. The file should contain only your API key, for example:

   fal_1234567890abcdef
   

4. Note: The .fal_key file is already in .gitignore for security

Option 2: Set environment variable

export FAL_KEY="your_fal_api_key_here"

Usage

1. Find the Fal Kontext API node in the image/generation category
2. Connect an input image to the image input
3. Enter your prompt describing the desired transformation
4. Adjust settings:
   • seed: Specific seed for reproducibility (-1 for random)
   • disable_prompt_enhancement: Turn off AI prompt enhancement if needed

Node Inputs

• prompt (STRING): Text description of the desired image transformation
• image (IMAGE): Input image to transform
• seed (INT): Random seed (-1 for random, default: -1)
• disable_prompt_enhancement (BOOLEAN): Disable AI prompt enhancement (default: False)

Node Outputs

• image (IMAGE): Generated image as a single tensor
• info (STRING): API response information including:
  • Request ID
  • Seed used for generation
  • Safety check status (✓ passed or ⚠️ blocked)
  • Any error messages or warnings
• passed_nsfw_filtering (BOOLEAN): True if content passed safety checks, False if blocked
  • Designed to work with "save on true" nodes in ComfyUI
  • Returns True for safe content that should be saved
  • Returns False for blocked content that should be skipped

Example Prompts

• "Change the car color to red"
• "Convert to pencil sketch with natural graphite lines"
• "Transform to oil painting with visible brushstrokes"
• "It's now snowing, everything is covered in snow"
• "Using this style, a bunny, a dog and a cat are having a tea party"

Troubleshooting

Debug Mode

The node includes detailed debug logging to help diagnose issues. To disable debug output once everything is working:

1. Open nodes.py
2. Change DEBUG = True to DEBUG = False at the top of the file

Image Handling Errors

The node properly handles ComfyUI's tensor format (B, H, W, C) and converts between PIL images and tensors automatically.

API Key Issues

Ensure your Fal API key is properly set either as an environment variable or in the .fal_key file.

If you see an error like "FAL API KEY NOT FOUND!", follow these steps:

1. Make sure you have created the .fal_key file in the ComfyUI-Kontext-API directory (not in ComfyUI root)
2. Check that the file contains only your API key with no extra spaces or quotes
3. Verify the key is valid by testing it on fal.ai

Dependencies

Make sure you have installed all required packages:

pip install fal-client Pillow numpy torch

License

This project is licensed under the MIT License - see the LICENSE file for details.