# FLUX.1 [pro] Fill

> FLUX.1 [pro] Fill is a high-performance endpoint for the FLUX.1 [pro] model that enables rapid transformation of existing images, delivering high-quality style transfers and image modifications with the core FLUX capabilities.


## Overview

- **Endpoint**: `https://fal.run/fal-ai/flux-pro/v1/fill`
- **Model ID**: `fal-ai/flux-pro/v1/fill`
- **Category**: image-to-image
- **Kind**: inference
**Tags**: editing



## Pricing

- **Price**: $0.05 per megapixels

For more details, see [fal.ai pricing](https://fal.ai/pricing).

## API Information

This model can be used via our HTTP API or more conveniently via our client libraries.
See the input and output schema below, as well as the usage examples.


### Input Schema

The API accepts the following input parameters:


- **`prompt`** (`string`, _required_):
  The prompt to fill the masked part of the image.
  - Examples: "A knight in shining armour holding a greatshield with \"FAL\" on it"

- **`seed`** (`integer`, _optional_):
  The same seed and the same prompt given to the same version of the model
  will output the same image every time.

- **`sync_mode`** (`boolean`, _optional_):
  If `True`, the media will be returned as a data URI and the output data won't be available in the request history.
  - Default: `false`

- **`num_images`** (`integer`, _optional_):
  The number of images to generate. Default value: `1`
  - Default: `1`
  - Range: `1` to `4`

- **`output_format`** (`OutputFormatEnum`, _optional_):
  The format of the generated image. Default value: `"jpeg"`
  - Default: `"jpeg"`
  - Options: `"jpeg"`, `"png"`

- **`safety_tolerance`** (`SafetyToleranceEnum`, _optional_):
  The safety tolerance level for the generated image. 1 being the most strict and 5 being the most permissive. Default value: `"2"`
  - Default: `"2"`
  - Options: `"1"`, `"2"`, `"3"`, `"4"`, `"5"`, `"6"`

- **`enhance_prompt`** (`boolean`, _optional_):
  Whether to enhance the prompt for better results.
  - Default: `false`

- **`image_url`** (`string`, _required_):
  The image URL to generate an image from. Needs to match the dimensions of the mask.
  - Examples: "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg"

- **`mask_url`** (`string`, _required_):
  The mask URL to inpaint the image. Needs to match the dimensions of the input image.
  - Examples: "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"



**Required Parameters Example**:

```json
{
  "prompt": "A knight in shining armour holding a greatshield with \"FAL\" on it",
  "image_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg",
  "mask_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"
}
```

**Full Example**:

```json
{
  "prompt": "A knight in shining armour holding a greatshield with \"FAL\" on it",
  "num_images": 1,
  "output_format": "jpeg",
  "safety_tolerance": "2",
  "image_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg",
  "mask_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"
}
```


### Output Schema

The API returns the following output format:

- **`images`** (`list<registry__image__fast_sdxl__models__Image>`, _required_):
  The generated image files info.
  - Array of registry__image__fast_sdxl__models__Image

- **`timings`** (`Timings`, _required_)

- **`seed`** (`integer`, _required_):
  Seed of the generated Image. It will be the same value of the one passed in the
  input or the randomly generated that was used in case none was passed.

- **`has_nsfw_concepts`** (`list<boolean>`, _required_):
  Whether the generated images contain NSFW concepts.
  - Array of boolean

- **`prompt`** (`string`, _required_):
  The prompt used for generating the image.



**Example Response**:

```json
{
  "images": [
    {
      "url": "",
      "content_type": "image/jpeg"
    }
  ],
  "prompt": ""
}
```


## Usage Examples

### cURL

```bash
curl --request POST \
  --url https://fal.run/fal-ai/flux-pro/v1/fill \
  --header "Authorization: Key $FAL_KEY" \
  --header "Content-Type: application/json" \
  --data '{
     "prompt": "A knight in shining armour holding a greatshield with \"FAL\" on it",
     "image_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg",
     "mask_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"
   }'
```

### Python

Ensure you have the Python client installed:

```bash
pip install fal-client
```

Then use the API client to make requests:

```python
import fal_client

def on_queue_update(update):
    if isinstance(update, fal_client.InProgress):
        for log in update.logs:
           print(log["message"])

result = fal_client.subscribe(
    "fal-ai/flux-pro/v1/fill",
    arguments={
        "prompt": "A knight in shining armour holding a greatshield with \"FAL\" on it",
        "image_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg",
        "mask_url": "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"
    },
    with_logs=True,
    on_queue_update=on_queue_update,
)
print(result)
```

### JavaScript

Ensure you have the JavaScript client installed:

```bash
npm install --save @fal-ai/client
```

Then use the API client to make requests:

```javascript
import { fal } from "@fal-ai/client";

const result = await fal.subscribe("fal-ai/flux-pro/v1/fill", {
  input: {
    prompt: "A knight in shining armour holding a greatshield with \"FAL\" on it",
    image_url: "https://storage.googleapis.com/falserverless/flux-lora/example-images/knight.jpeg",
    mask_url: "https://storage.googleapis.com/falserverless/flux-lora/example-images/mask_knight.jpeg"
  },
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);
```


## Additional Resources

### Documentation

- [Model Playground](https://fal.ai/models/fal-ai/flux-pro/v1/fill)
- [API Documentation](https://fal.ai/models/fal-ai/flux-pro/v1/fill/api)
- [OpenAPI Schema](https://fal.ai/api/openapi/queue/openapi.json?endpoint_id=fal-ai/flux-pro/v1/fill)

### fal.ai Platform

- [Platform Documentation](https://docs.fal.ai)
- [Python Client](https://docs.fal.ai/clients/python)
- [JavaScript Client](https://docs.fal.ai/clients/javascript)