black-forest-labs/flux-kontext-max/text-to-image API

This document provides details on the input and output parameters for the black-forest-labs/flux-kontext-max/text-to-image model API, aiding you in understanding the meaning of fields when using the API.

Request Parameters

Request Body

Field Name	Type	Required	Default	Description
prompt	string	Required	-	Prompt
model	string	Required	-	The model name used for this request, which should be `black-forest-labs/flux-kontext-max/text-to-image`.
n	int	Optional	1	Number of images to generate, ranging from 1 to 4
aspect_ratio	string	Optional	”1:1”	Aspect ratio of the image in the format “width:height”, e.g., “16:9” or “1:1”. Supported dimensions: “21:9”, “16:9”, “4:3”, “3:2”, “1:1”, “2:3”, “3:4”, “9:16”, “9:21”
seed	int	Optional	-1	Random seed used to control the randomness of the model output. If you want the generated content to remain consistent, use the same seed value.
steps	int	Optional	20	Number of inference steps, ranging from 1 to 50
guidance_scale	float	Optional	2.5	Degree of relevance between model output and prompt, i.e., the freedom of the generated image; the larger the value, the lower the freedom of the model, resulting in stronger relevance to the user’s prompt. Value range: [1, 10].
negative_prompt	string	Optional	-	Negative prompt, used to specify content you do not wish to appear in the generated image
response_format	string	Optional	”url”	Specifies the format to return the generated image in, default is `url`, options include `b64_json`

Response Parameters

Field Name	Type	Description
created	`integer`	Unix timestamp (seconds) of the creation time of this request.
data	`array`	Information of the output images, including the URL for downloading the image or the Base64 encoding. • If the format of the generated image return is specified as url, the corresponding subfield is url; • If specified as b64_json, the corresponding subfield is b64_json. 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

Examples

OPENAI Compatible Interface

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

Synchronous Request


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-max/text-to-image",
    "prompt": "Convert to quick pencil sketch",
    "aspect_ratio": "16:9"
}'


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-max/text-to-image",
    prompt="Convert to quick pencil sketch",
    extra_body={
        "aspect_ratio": "16:9"
    }
)
 
print(response.data[0].url)

Response


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


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