# black-forest-labs/flux-kontext-pro/text-to-image API

This document introduces the input and output parameters of the `black-forest-labs/flux-kontext-pro/text-to-image` model call API for your reference when using the interface.

---

## Request Parameters

### Request Body

| Field Name      | Type   | Required | Default | Description                                                                                                                                  |
| --------------- | ------ | -------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| prompt          | string | Required | -       | Prompt words                                                                                                                                |
| model           | string | Required | -       | The model name used for this request, here it is `black-forest-labs/flux-kontext-pro/text-to-image`.                                         |
| n               | int    | Optional | 1       | Number of images to generate, range 1~4                                                                                                      |
| aspect_ratio    | string | Optional | "1:1"   | The aspect ratio of the image, formatted as "width:height", e.g. "16:9" or "1:1".<br>Supported sizes: "21:9", "16:9", "4:3", "3:2", "1:1", "2:3", "3:4", "9:16", "9:21" |
| seed            | int    | Optional | -1      | Random seed to control the randomness of the model's generated content. If you want the generated content to remain consistent, you can use the same seed parameter value. |
| steps           | int    | Optional | 20      | Number of inferences, range 1~50                                                                                                              |
| guidance_scale  | float  | Optional | 2.5     | The degree of consistency between the model output and the prompt, i.e., the degree of freedom of generated images; the larger the value, the smaller the model's freedom, and the stronger the correlation with the user's input prompts.<br>Range [1, 10].           |
| negative_prompt | string | Optional | -       | Negative prompt words for specifying content that should not appear in the generated image                                                   |
| response_format | string | Optional | "url"   | Specifies the format of the generated image returned, default is `url`, optional `b64_json`                                                  |

## Response Parameters

| Field Name    | Type      | Description                                                                                                                                                                           |
| ------------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| created       | `integer` | Unix timestamp (in seconds) of when this request was created.                                                                                                                                                      |
| data          | `array`   | Information of the output image, including the download URL or Base64.<br>• When specifying the format of the generated image as url, the child field of the corresponding parameter is url; <br>• When specifying the format of the generated image as b64_json, the child field of the corresponding parameter is b64_json.<br>Note: The link will expire within 7 days after generation, please save the image promptly. |
| error         | `Object`  | Error information object                                                                                                                                                       |
| error.code    | `string`  | Error code                                                                                                                                                                          |
| error.message | `string`  | Error message                                                                                                                                                                       |
| error.param   | `string`  | Request id                                                                                                                                                                          |

## Example

### OPENAI Compatible Interface

`POST https://api.umodelverse.ai/v1/images/generations`

#### Synchronous Request

```bash
curl --location 'https://api.umodelverse.ai/v1/images/generations' \
--header "Authorization: Bearer $MODELVERSE_API_KEY" \
--header 'Content-Type: application/json' \
--data '{
    "model": "black-forest-labs/flux-kontext-pro/text-to-image",
    "prompt": "Convert to quick pencil sketch",
    "aspect_ratio": "9:16"
}'
```

```python
import os
from openai import OpenAI

client = OpenAI(
    base_url=os.getenv("BASE_URL", "https://api.umodelverse.ai/v1"),
    api_key=os.getenv("API_KEY", "$MODELVERSE_API_KEY")
)

response = client.images.generate(
    model="black-forest-labs/flux-kontext-pro/text-to-image",
    prompt="Convert to quick pencil sketch",
    extra_body={
        "aspect_ratio": "9:16"
    }
)

print(response.data[0].url)
```

### Response

```json
{
  "created": 1750667997,
  "data": [
    {
      "url": "https://xxxxx/xxxx.png",
      "b64_json": "data:image/png;base64,{image_base64_string}"
    }
  ],
  "usage": {
    "input_tokens_details": {}
  }
}
```

```json
{
  "error": {
    "message": "error_message",
    "type": "error_type",
    "param": "request_id",
    "code": "error_code"
  }
}
```

<!--
TODO: Asynchronous Request
### Asynchronous Request

``` -->