Black Forest Labs Image Generation

Black Forest Labs provides state-of-the-art text-to-image generation using their FLUX models.

Overview

Property	Details
Description	Black Forest Labs FLUX models for high-quality text-to-image generation
Provider Route on LiteLLM	black_forest_labs/
Provider Doc	Black Forest Labs API ↗
Supported Operations	/images/generations

Setup

API Key

import os

# Set your Black Forest Labs API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

Get your API key from Black Forest Labs.

Supported Models

Model Name	Description	Price
black_forest_labs/flux-pro-1.1	Fast & reliable standard generation	$0.04/image
black_forest_labs/flux-pro-1.1-ultra	Ultra high-resolution (up to 4MP)	$0.06/image
black_forest_labs/flux-dev	Development/open-source variant	$0.025/image
black_forest_labs/flux-pro	Original pro model	$0.05/image

Image Generation

Usage - LiteLLM Python SDK

Basic Usage

Basic Image Generation

import os
import litellm

# Set your API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

# Generate an image
response = litellm.image_generation(
    model="black_forest_labs/flux-pro-1.1",
    prompt="A beautiful sunset over the ocean with sailing boats",
)

# BFL returns URLs
print(response.data[0].url)

Async Usage

Async Image Generation

import os
import asyncio
import litellm

# Set your API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

async def generate_image():
    response = await litellm.aimage_generation(
        model="black_forest_labs/flux-pro-1.1",
        prompt="A futuristic city skyline at night",
    )
    print(response.data[0].url)

# Run the async function
asyncio.run(generate_image())

Custom Size

Image Generation with Custom Size

import os
import litellm

# Set your API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

# Generate with specific dimensions
response = litellm.image_generation(
    model="black_forest_labs/flux-pro-1.1",
    prompt="A majestic mountain landscape",
    size="1792x1024",  # Maps to width/height
)

print(response.data[0].url)

Ultra High-Res

Ultra High Resolution with flux-pro-1.1-ultra

import os
import litellm

# Set your API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

# Generate ultra high-resolution image
response = litellm.image_generation(
    model="black_forest_labs/flux-pro-1.1-ultra",
    prompt="Detailed portrait of a fantasy character",
    size="2048x2048",    # Up to 4MP supported
    quality="hd",        # Maps to raw=True for natural look
)

print(response.data[0].url)

Advanced Parameters

Advanced Image Generation with BFL Parameters

import os
import litellm

# Set your API key
os.environ["BFL_API_KEY"] = "your-api-key-here"

# Generate with BFL-specific parameters
response = litellm.image_generation(
    model="black_forest_labs/flux-pro-1.1",
    prompt="A cute orange cat sitting on a windowsill",
    seed=42,                    # For reproducible results
    output_format="png",        # png or jpeg
    safety_tolerance=2,         # 0-6, higher = more permissive
    prompt_upsampling=True,     # Enhance prompt for better results
)

print(response.data[0].url)

Usage - LiteLLM Proxy Server

1. Configure your config.yaml

Black Forest Labs Image Generation Configuration

model_list:
  - model_name: flux-pro
    litellm_params:
      model: black_forest_labs/flux-pro-1.1
      api_key: os.environ/BFL_API_KEY
    model_info:
      mode: image_generation

  - model_name: flux-ultra
    litellm_params:
      model: black_forest_labs/flux-pro-1.1-ultra
      api_key: os.environ/BFL_API_KEY
    model_info:
      mode: image_generation

  - model_name: flux-dev
    litellm_params:
      model: black_forest_labs/flux-dev
      api_key: os.environ/BFL_API_KEY
    model_info:
      mode: image_generation

general_settings:
  master_key: sk-1234

2. Start LiteLLM Proxy Server

Start LiteLLM Proxy Server

litellm --config /path/to/config.yaml

# RUNNING on http://0.0.0.0:4000

3. Make image generation requests

OpenAI SDK

Black Forest Labs via Proxy - OpenAI SDK

from openai import OpenAI

# Initialize client with your proxy URL
client = OpenAI(
    base_url="http://localhost:4000",
    api_key="sk-1234"
)

# Generate image with FLUX Pro
response = client.images.generate(
    model="flux-pro",
    prompt="A beautiful garden with colorful flowers",
    size="1024x1024",
)

print(response.data[0].url)

cURL

Black Forest Labs via Proxy - cURL

curl -X POST 'http://localhost:4000/v1/images/generations' \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer sk-1234' \
  -d '{
    "model": "flux-pro",
    "prompt": "A beautiful garden with colorful flowers",
    "size": "1024x1024"
  }'

Supported Parameters

OpenAI-Compatible Parameters

Parameter	Type	Description	Mapping
prompt	string	Text description of the image to generate	Direct
model	string	The FLUX model to use	Direct
size	string	Image dimensions (e.g., 1024x1024)	Maps to width and height
n	integer	Number of images (ultra model only, up to 4)	Maps to num_images
quality	string	hd for natural look	Maps to raw=True for ultra
response_format	string	url or b64_json	Direct

Black Forest Labs Specific Parameters

Parameter	Type	Description	Default
width	integer	Image width (256-1920, multiples of 16)	1024
height	integer	Image height (256-1920, multiples of 16)	1024
aspect_ratio	string	Alternative to width/height (e.g., 16:9, 1:1)	-
seed	integer	Seed for reproducible results	Random
output_format	string	Output format: png or jpeg	png
safety_tolerance	integer	Safety filter tolerance (0-6, higher = more permissive)	2
prompt_upsampling	boolean	Enhance prompt for better results	false

Ultra Model Specific Parameters

Parameter	Type	Description	Default
raw	boolean	Raw mode for more natural, less synthetic look	false
num_images	integer	Number of images to generate (1-4)	1

How It Works

Black Forest Labs uses a polling-based API:

1. Submit Request: LiteLLM sends your prompt to BFL
2. Get Task ID: BFL returns a task ID and polling URL
3. Poll for Result: LiteLLM automatically polls until the image is ready
4. Return Result: The generated image URL is returned

This polling is handled automatically by LiteLLM - you just call image_generation() and get the result.

Getting Started

1. Create an account at Black Forest Labs
2. Get your API key from the dashboard
3. Set your BFL_API_KEY environment variable
4. Use litellm.image_generation() with any supported model

Additional Resources

• Black Forest Labs Documentation
• Black Forest Labs Image Editing - For editing existing images
• FLUX Model Information