Black Forest LabsMediumUltra

FLUX 1.1 Pro Ultra

FLUX1.1 [pro] in ultra and raw modes. Images are up to 4 megapixels — the highest-resolution tier of the FLUX 1.1 Pro family. Use raw mode for realism.

140 credits

per image

Up to 4-megapixel ultra-resolution output

Raw mode for less processed, more natural-looking images

Flux Redux image_prompt support for composition guidance

Wide range of aspect ratios (21:9 to 9:21)

Adjustable safety tolerance

Run it right now

Test this model instantly in the Console Playground — no code required

Use with AI Assistant

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llms.txtllms.txt ↗

Quick Start

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "black-forest-labs/flux-1.1-pro-ultra",
  "input": {
    "prompt": "a majestic snow-capped mountain peak bathed in a warm glow of the setting sun",
    "aspect_ratio": "3:2",
    "raw": false
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`prompt`	string	Yes	-	Text prompt for image generation
`raw`	boolean	No	false	Generate less processed, more natural-looking images
`image_prompt`	string	No	-	Image to guide composition via Flux Redux, blended with the text prompt
`image_prompt_strength`	number	No	0.1	Blend strength between the text prompt and the image prompt (0-1)
`aspect_ratio`	string	No	1:1	Aspect ratio for the generated image 21:916:93:24:35:41:14:53:42:39:169:21
`safety_tolerance`	integer	No	2	Safety tolerance, 1 is most strict and 6 is most permissive
`output_format`	string	No	jpg	Format of the output images jpgpng
`seed`	integer	No	-	Random seed. Set for reproducible generation

How to Provide File Input

There are 3 ways to provide files for the image_prompt parameter:

Recommended

Direct Upload (Multipart)

Attach files directly to POST /v1/predictions/upload. No separate upload step needed.

curl -X POST "https://api.core.today/v1/predictions/upload" \
  -H "X-API-Key: cdt_your_api_key" \
  -F "model=black-forest-labs/flux-1.1-pro-ultra" \
  -F 'input={"prompt":"your prompt here"}' \
  -F "file:image_prompt=@your_file.png"

Image URL

Pass a publicly accessible URL directly. You can also use file_url from the Storage API.

{
  "model": "black-forest-labs/flux-1.1-pro-ultra",
  "input": {
    "prompt": "your prompt here",
    "image_prompt": "https://example.com/image.jpg"
  }
}

See the File Upload docs for more upload methods including Presigned URLs.

Common Parameters

Common parameters used when calling POST /v1/predictions.

Parameter	Type	Required	Default	Description
`model`	string	Yes	-	Model identifier
`input`	object	Yes	-	Object containing the model-specific parameters from the table above
`output_folder`	string	No	-	Folder path for output files (max 256 chars, '..' not allowed)
`webhook_url`	string	No	-	Webhook URL to call on completion
`is_public`	boolean	No	false	If true, output files are also available via permanent public URLs

Examples

Landscape Photography

High-resolution scenic landscape at 3:2 aspect ratio

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "black-forest-labs/flux-1.1-pro-ultra",
  "input": {
    "prompt": "a majestic snow-capped mountain peak bathed in a warm glow of the setting sun",
    "aspect_ratio": "3:2",
    "raw": false
  }
}'

Raw Mode Portrait

Natural-looking, less processed portrait using raw mode

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "black-forest-labs/flux-1.1-pro-ultra",
  "input": {
    "prompt": "a candid portrait of a chef in a busy kitchen, natural lighting",
    "raw": true,
    "aspect_ratio": "4:5"
  }
}'