MODEL ID bfl:1@3

live

FLUX.1 Expand [pro]

by Black Forest Labs November 21, 2024

FLUX.1 Expand [pro] is an outpainting model that extends images beyond their original frame while preserving structure, lighting, and style. It supports controlled expansion from real or generated inputs and integrates into image editing or generative workflows that need precise, coherent borders.

API Options

Platform-level options for task execution and delivery.

taskType string required value: imageInference: Identifier for the type of task being performed

taskUUID string required UUID v4: UUID v4 identifier for tracking tasks and matching async responses. Must be unique per task.

outputType string default: URL: Image output type.

Allowed values 3 values

outputFormat string default: JPG

Specifies the file format of the generated output. The available values depend on the task type and the specific model's capabilities.

`JPG`: Best for photorealistic images with smaller file sizes (no transparency).
`PNG`: Lossless compression, supports high quality and transparency (alpha channel).
`WEBP`: Modern format providing superior compression and transparency support.

**Transparency**: If you are using features like background removal or LayerDiffuse that require transparency, you must select a format that supports an alpha channel (e.g., `PNG`, `WEBP`, `TIFF`). `JPG` does not support transparency.

Allowed values 3 values

outputQuality integer min: 20 max: 99 default: 95: Compression quality of the output. Higher values preserve quality but increase file size.

webhookURL string URI

Specifies a webhook URL where JSON responses will be sent via HTTP POST when generation tasks complete. For batch requests with multiple results, each completed item triggers a separate webhook call as it becomes available.

Learn more 1 resource

Webhooks
PLATFORM

deliveryMethod string default: sync

Determines how the API delivers task results.

Allowed values 2 values

: Returns complete results directly in the API response.
: Returns an immediate acknowledgment with the task UUID. Poll for results using getResponse.

Learn more 1 resource

Task Polling
PLATFORM

uploadEndpoint string URI

Specifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the media file is sent directly as the request body. For secure uploads to cloud storage, use presigned URLs that include temporary authentication credentials.

Common use cases:

Cloud storage: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage using presigned URLs.
CDN integration: Upload to content delivery networks for immediate distribution.

// S3 presigned URL for secure upload
https://your-bucket.s3.amazonaws.com/generated/content.mp4?X-Amz-Signature=abc123&X-Amz-Expires=3600

// Google Cloud Storage presigned URL
https://storage.googleapis.com/your-bucket/content.jpg?X-Goog-Signature=xyz789

// Custom storage endpoint
https://storage.example.com/uploads/generated-image.jpg

The content data will be sent as the request body to the specified URL when generation is complete.

safety object

Content safety checking configuration for image generation.

Properties 2 properties

safety » checkContent checkContent boolean default: false: Enable or disable content safety checking. When enabled, defaults to fast mode.

safety » mode mode string default: none

Safety checking mode for image generation.

Allowed values 2 values

: Disables checking.
: Performs a single check.

ttl integer min: 60: Time-to-live (TTL) in seconds for generated content. Only applies when outputType is URL.

includeCost boolean default: false: Include task cost in the response.

numberResults integer min: 1 max: 20 default: 1: Number of results to generate. Each result uses a different seed, producing variations of the same parameters.

Inputs

Input resources for the task (images, audio, etc). These must be nested inside the inputs object.

inputs » seedImage seedImage string required

Image used as a starting point for the generation (UUID, URL, Data URI, or Base64).

Learn more 3 resources

Generation Parameters

Core parameters for controlling the generated content.

model string required value: bfl:1@3

Identifier of the model to use for generation.

Learn more 3 resources

positivePrompt string required min: 2 max: 3000

Text prompt describing elements to include in the generated output.

Learn more 2 resources

steps integer min: 15 max: 50 default: 50

Total number of denoising steps. Higher values generally produce more detailed results but take longer.

Learn more 1 resource

Text To Image: Steps Trading Quality For Speed
GUIDE

CFGScale float min: 1.5 max: 100 step: 0.01 default: 60

Guidance scale representing how closely the output will resemble the prompt. Higher values produce results more aligned with the prompt.

Learn more 1 resource

Text To Image: Cfg Scale Balancing Creativity And Control
GUIDE

outpaint object required

Extends image boundaries in specified directions. Final width/height must account for original image plus extensions.

Learn more 1 resource

Image Outpainting: Outpaint Defining The Expansion
GUIDE

Properties 4 properties

outpaint » bottom bottom integer min: 0 max: 2048 step: 64: Number of pixels to extend to the bottom.

outpaint » left left integer min: 0 max: 2048 step: 64: Number of pixels to extend to the left.

outpaint » right right integer min: 0 max: 2048 step: 64: Number of pixels to extend to the right.

outpaint » top top integer min: 0 max: 2048 step: 64: Number of pixels to extend to the top.

Provider Settings

Parameters specific to this model provider. These must be nested inside the providerSettings.bfl object.

providerSettings » bfl » promptUpsampling promptUpsampling boolean default: false: Enable automatic enhancement and expansion of the input prompt.

providerSettings » bfl » safetyTolerance safetyTolerance integer min: 0 max: 6 default: 2: Tolerance level for content moderation. Lower values are stricter; higher values are more permissive.

taskType string required value: imageInference: Type of the task.

taskUUID string required UUID v4: UUID of the task.

imageUUID string required UUID v4: UUID of the output image.

imageURL string URI: URL of the output image.

imageBase64Data string: Base64-encoded image data.

imageDataURI string URI: Data URI of the output image.

seed integer: The seed used for generation. If none was provided, shows the randomly generated seed.

NSFWContent boolean: Flag indicating if NSFW content was detected.

cost float: Task cost in USD. Present when includeCost is set to true in the request.

Image to Image

Moonlit Marsh Caravan Encampment

Request

{
  "taskType": "imageInference",
  "taskUUID": "567a4534-6ee4-464a-8a66-3ba4be47cd3e",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the scene outward into a broad moonlit marsh landscape surrounding the existing caravan encampment. Preserve the original wagon, mule, travelers, firelight, and cool lunar illumination. Add winding reflective water channels, clumps of reeds, distant cypress silhouettes, low drifting mist, scattered bedrolls and travel crates near the camp, faint wheel tracks fading into wet ground, a far treeline, and a dramatic open sky with layered clouds around a bright moon. Maintain realistic cinematic detail, natural perspective, seamless continuity, and balanced negative space around the central camp.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 384,
    "right": 384,
    "top": 256,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/552fdf32-900e-434b-8f50-ad876925ccc8.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "567a4534-6ee4-464a-8a66-3ba4be47cd3e",
  "imageUUID": "1b2519f3-5b22-4a54-89c2-c0a53e43e592",
  "imageURL": "https://im.runware.ai/image/os/a16d07/ws/2/ii/1b2519f3-5b22-4a54-89c2-c0a53e43e592.jpg",
  "seed": 2141894651,
  "cost": 0.05
}

Image to Image

Grand Aquarium Rotunda Expansion

Request

{
  "taskType": "imageInference",
  "taskUUID": "9a48ce30-8355-4b7f-9e15-617b5f8a4fd7",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the existing aquarium rotunda beyond the original frame with seamless architectural continuity: more sweeping arches, vaulted ceiling ribs, suspended directional signs, additional cylindrical side tanks, reflective stone flooring, benches, distant visitors, subtle refractions from the water, soft teal glow balanced with warm interior lighting, realistic perspective lines, refined high-end public space design, richly detailed but natural, cohesive materials and shadows, photographic realism",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 384,
    "right": 384,
    "top": 256,
    "bottom": 320
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/10ab549f-109e-4c55-b256-e18aa74c6f1d.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "9a48ce30-8355-4b7f-9e15-617b5f8a4fd7",
  "imageUUID": "c41386bd-a690-4215-94ea-5271c72c1524",
  "imageURL": "https://im.runware.ai/image/os/a05d22/ws/2/ii/c41386bd-a690-4215-94ea-5271c72c1524.jpg",
  "seed": 1556062672,
  "cost": 0.05
}

Image to Image

Glacial Viaduct Panorama Expansion

Request

{
  "taskType": "imageInference",
  "taskUUID": "22ed3e04-4497-4e68-a3b5-61811c85a92e",
  "model": "bfl:1@3",
  "positivePrompt": "Extend the existing glacier-valley viaduct scene into a grand panoramic vista. Preserve the original bridge, train, scale, perspective, and blue-hour dawn lighting. Reveal towering snow-covered peaks beyond the current frame, additional fractured ice fields below, wind-carved ridges, faint alpine clouds catching pale pink sunlight, and deeper valley depth on both sides. Keep the image photorealistic, cinematic, crisp, and geographically believable, with seamless continuation of stone texture, rail lines, mist layers, shadows, and atmospheric depth.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "top": 512,
    "left": 384,
    "right": 384,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/c41d1e74-79ec-4066-8e6a-ac529129eba1.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "22ed3e04-4497-4e68-a3b5-61811c85a92e",
  "imageUUID": "b84d218b-4907-42eb-b0b8-754e212912e0",
  "imageURL": "https://im.runware.ai/image/os/a10d08/ws/2/ii/b84d218b-4907-42eb-b0b8-754e212912e0.jpg",
  "seed": 1238429443,
  "cost": 0.05
}

Image to Image

Cliffside Monastery Dawn Expansion

Request

{
  "taskType": "imageInference",
  "taskUUID": "f6f41d51-db5f-45ce-8b36-89c9860a9602",
  "model": "bfl:1@3",
  "positivePrompt": "Expand the scene outward into a grand panoramic mountain sanctuary. Preserve the original cliffside monastery, stone materials, perspective, and soft dawn light. Add vast surrounding rock walls, layered alpine peaks fading into the distance, a winding path chiselled into the cliffs, suspended rope bridges, sparse wind-shaped pines, low valley mist, subtle birds circling far away, and golden sunlight catching ridgelines. Keep the image realistic, serene, majestic, and compositionally seamless with natural atmospheric perspective.",
  "steps": 40,
  "CFGScale": 55,
  "outpaint": {
    "left": 512,
    "right": 512,
    "top": 256,
    "bottom": 256
  },
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/e968767b-577b-4e44-aab2-922c656d5470.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "f6f41d51-db5f-45ce-8b36-89c9860a9602",
  "imageUUID": "ef43418c-8f03-4fcc-9509-635e2737d651",
  "imageURL": "https://im.runware.ai/image/os/a11d13/ws/2/ii/ef43418c-8f03-4fcc-9509-635e2737d651.jpg",
  "seed": 367135997,
  "cost": 0.05
}