MODEL ID bfl:1@2

live

FLUX.1 Fill [pro]

by Black Forest Labs November 1, 2024

FLUX.1 Fill Pro provides advanced inpainting and outpainting for real and generated images. Supply an input image, mask, and text prompt. The model fills or extends regions with seamless content that matches context and style. Ideal for edits, layout fixes, and content-aware expansion.

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

inputs » maskImage maskImage string required

Image used to specify which areas of the seed image should be edited (UUID, URL, Data URI, or Base64).

Learn more 1 resource

Image Inpainting: Seed And Mask Image The Foundation
GUIDE

Generation Parameters

Core parameters for controlling the generated content.

model string required value: bfl:1@2

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

seed integer min: 0 max: 9223372036854776000

Random seed for reproducible generation. When not provided, a random seed is generated in the unsigned 32-bit range.

Learn more 1 resource

Text To Image: Seed Controlling Randomness Deterministically
GUIDE

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

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

Grand Concourse Ceiling Extension

Request

{
  "taskType": "imageInference",
  "taskUUID": "46584b86-45d6-44b2-9dbb-721b15a97caf",
  "model": "bfl:1@2",
  "positivePrompt": "Extend the historic railway concourse beyond the cropped frame with a majestic vaulted ceiling, ribbed arches, clerestory windows, carved stone ornament, suspended destination boards, subtle dust in sunbeams, and additional architectural depth. Keep the original camera angle, realistic lens perspective, natural daylight, balanced symmetry, and documentary photo realism. Match the existing stone color, floor reflections, crowd density, and atmosphere so the new areas feel natively captured in the same shot.",
  "seed": 51031,
  "steps": 40,
  "CFGScale": 55,
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/e4f7c3e9-0821-47ff-8cd4-b19ea48da36e.jpg",
    "maskImage": "https://assets.runware.ai/assets/inputs/6c3b7dcb-4bef-4759-bc50-5dd601c54bec.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "46584b86-45d6-44b2-9dbb-721b15a97caf",
  "imageUUID": "7dd99220-5722-4902-916e-06720ed62f1d",
  "imageURL": "https://im.runware.ai/image/os/a15d18/ws/2/ii/7dd99220-5722-4902-916e-06720ed62f1d.jpg",
  "seed": 51031,
  "cost": 0.05
}

Image to Image

Deserted Salt Cathedral Excavation

Request

{
  "taskType": "imageInference",
  "taskUUID": "b5c675b5-8025-44f9-8726-e42ae52767aa",
  "model": "bfl:1@2",
  "positivePrompt": "Extend the scene into an immense subterranean salt cathedral excavation, preserving the existing documentary photography style. Reveal towering crystalline salt pillars, chiseled vaults, collapsed alcoves, suspended survey lines, scattered excavation tools, stratified mineral textures, faint haze in the distance, and additional pools of warm work light fading into cool shadow. The new areas should feel historically mysterious yet believable, with seamless perspective, natural geological continuity, realistic scale, subtle human activity traces, and cohesive color matching to the original chamber.",
  "seed": 50554,
  "steps": 50,
  "CFGScale": 60,
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/282ae2c5-6a1c-4fa2-a5c8-9af78ec43208.jpg",
    "maskImage": "https://assets.runware.ai/assets/inputs/7d41188e-abd9-4ffc-893c-c800c545ce62.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "b5c675b5-8025-44f9-8726-e42ae52767aa",
  "imageUUID": "4a77a892-9294-4c7a-b71c-d84fd2219e44",
  "imageURL": "https://im.runware.ai/image/os/a25d05/ws/2/ii/4a77a892-9294-4c7a-b71c-d84fd2219e44.jpg",
  "seed": 50554,
  "cost": 0.05
}

Image to Image

Deserted Aquarium Tunnel Extension

Request

{
  "taskType": "imageInference",
  "taskUUID": "2be69c27-89a3-41bf-b845-533332b4a93f",
  "model": "bfl:1@2",
  "positivePrompt": "Extend the abandoned aquarium tunnel outward on both sides with seamless architectural continuation. Add more curved glass passage, repeating rib supports, dim emergency floor lights, drifting suspended particles, wavering caustic reflections, and deeper aquatic space beyond the glass with rays, fish silhouettes, and hints of large tank structures. Preserve the original camera angle, realistic materials, moody hush, and cinematic realism. The new areas should feel naturally connected, detailed, and consistent with the existing scene.",
  "seed": 72929,
  "steps": 40,
  "CFGScale": 55,
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/be68f81d-610e-456c-a68a-b66fa7251f8d.jpg",
    "maskImage": "https://assets.runware.ai/assets/inputs/abd462db-d01d-42a8-a026-c8879a33bf4a.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "2be69c27-89a3-41bf-b845-533332b4a93f",
  "imageUUID": "b964cf69-778c-47a7-9a86-5923eb15e936",
  "imageURL": "https://im.runware.ai/image/os/a03d21/ws/2/ii/b964cf69-778c-47a7-9a86-5923eb15e936.jpg",
  "seed": 72929,
  "cost": 0.05
}

Image to Image

Submerged Metro Platform Expansion

Request

{
  "taskType": "imageInference",
  "taskUUID": "713ec957-60c1-418e-b138-ba4890044b31",
  "model": "bfl:1@2",
  "positivePrompt": "Extend the scene into a vast abandoned metro terminal partially submerged in still water, continuing the existing platform naturally. Add receding tiled columns, broken route maps, dangling electrical cables, moss and climbing plants creeping through cracked concrete, scattered luggage half-submerged near the far wall, a distant tunnel mouth, reflections in the water, soft shafts of pale morning light filtering from unseen street grates above, realistic textures, grounded cinematic atmosphere, seamless perspective, coherent architectural continuity, highly detailed environmental realism.",
  "seed": 66529,
  "steps": 50,
  "CFGScale": 60,
  "providerSettings": {
    "bfl": {
      "promptUpsampling": true,
      "safetyTolerance": 2
    }
  },
  "inputs": {
    "seedImage": "https://assets.runware.ai/assets/inputs/8b0a7001-50ed-4d93-88ba-ff246506f7fd.jpg",
    "maskImage": "https://assets.runware.ai/assets/inputs/654d91fe-c80c-4ca1-91db-07cfeb58cdba.jpg"
  }
}

Response

{
  "taskType": "imageInference",
  "taskUUID": "713ec957-60c1-418e-b138-ba4890044b31",
  "imageUUID": "be9a5e95-3a25-4e80-aec7-b014201b52d5",
  "imageURL": "https://im.runware.ai/image/os/a22d05/ws/2/ii/be9a5e95-3a25-4e80-aec7-b014201b52d5.jpg",
  "seed": 66529,
  "cost": 0.05
}