bfl/flux-subject
Flux Subject by BFL - generate stunning images from text prompts with state-of-the-art AI. Supports multiple aspect ratios, styles, and high-resolution output for creative and commercial use.
PNG, JPEG, WebP, or GIF · 20 MiB maximum
Example output — click Run to generate your own
Send your first request
OpenAI-compatible endpoint with unified authentication and usage tracking.
https://api.sandbase.ai/v1/runbfl/flux-subjectInput Schema
7 parameters · 2 required · 5 optional
| Parameter | Type | Required | Description |
|---|---|---|---|
image | string | Required | URL of image of the subject |
prompt | string | Required | The prompt to generate an image from. |
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. |
aspect_ratio | string | Optional | The aspect ratio of the generated image. · Options: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16 21:916:93:24:35:41:14:53:42:39:16 |
output_format | string | Optional | The format of the generated image. · Options: jpeg, png · Default: "png" jpegpng |
guidance_scale | number | Optional | The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you. · Min: 0 · Max: 20 · Default: 3.5 |
num_inference_steps | integer | Optional | The number of inference steps to perform. · Min: 1 · Max: 50 · Default: 8 |
Output Schema
| Field | Type | Description |
|---|---|---|
id | string | Unique identifier for the generation task |
status | string | Task status: pending, running, completed, failed, timeout |
model | string | Model used for the generation |
outputs | array | Array of output items |
outputs[].url | string | URL of the generated artifact |
outputs[].content_type | string | MIME type (e.g. image/png, video/mp4) |
error | object | null | Error details if failed, null on success |
error.type | string | Machine-readable error type code |
error.message | string | Human-readable error description |
Async Workflow
This model uses asynchronous execution. Submit a request and poll for the result.
- Submit — POST to /v1/run, receive an
id - Poll — GET /v1/run/{id} until status is
completed,failed, ortimeout - Retrieve — Read
outputsfrom the completed response
Code Examples
Ready-to-run snippets
# Step 1: Submit
curl -X POST https://api.sandbase.ai/v1/run \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"model": "bfl/flux-subject",
"image": "https://static.sandbase.ai/examples/bfl/flux-subject/input_image_0.jpg",
"prompt": "On the beach, a lady sits under a beach umbrella with 'Omini' written on it. She's wearing this shirt and has a big smile on her face, with her surfboard hehind her. The sun is setting in the background. The sky is a beautiful shade of orange and purple.",
"output_format": "png",
"guidance_scale": 3.5,
"num_inference_steps": 8
}'
# Step 2: Poll result (replace <id>)
curl https://api.sandbase.ai/v1/run/<id> \
-H "Authorization: Bearer YOUR_API_KEY"API README
FLUX.1 Subject
FLUX.1 Subject is a image generation and editing workflow in the FLUX family. Flux Subject by BFL - generate stunning images from text prompts with state-of-the-art AI. Supports multiple aspect ratios, styles, and high-resolution output for creative and commercial use. It is designed to translate deliberate creative direction and supplied reference material into a coherent production asset, with attention to subject identity, composition, visual detail, and the specific transformation implied by this exact route.
Use this route when the project needs a controlled visual generation or revision. Describe the intended result, what must remain recognizable, and the required composition, lighting, materials, atmosphere, and finish; keep technical delivery choices in the schema fields below.
Highlights
- Subject identity preservation. Carries a supplied subject’s recognizable visual traits into new scenes and compositions.
- Context replacement. Places the anchored subject into different environments, lighting, poses, and creative treatments.
- Reference-led generation. Uses visual subject information as an active generation condition rather than a loose style hint.
- Consistent campaign assets. Supports multiple creative variants that need the same person, character, or product to remain recognizable.
Pricing
| Configuration | Billing unit | Price |
|---|---|---|
| Base generation | Per request | $0.04 |
When to Use
| ✅ Good fit | ❌ Consider alternatives |
|---|---|
| The project needs this exact FLUX capability | The intended task belongs to a different media workflow |
| Required source and control media are available | Necessary assets or usage rights are unavailable |
| Creative direction can state change and preservation goals | Output must be deterministic at pixel or frame level |
| Supported dimensions and formats match final delivery | Placement requires unsupported specifications |
| An asynchronous generated result fits production | A live frame-synchronous response is mandatory |
Prompt Guide
Lead with the main subject and action, then specify composition, context, lighting, materials, style, typography, and atmosphere. For editing, identify each source and clearly separate the requested transformation from the subjects, regions, geometry, or identity that must remain unchanged.
{
"prompt": "A cinematic, precisely composed result with a clear subject, controlled camera or viewpoint, realistic lighting, exact materials, and intentional atmosphere",
"image": "https://example.com/reference.png",
"seed": 1,
"aspect_ratio": "21:9",
"output_format": "jpeg"
}
Technical Specs
| Spec | Value |
|---|---|
| Model ID | bfl/flux-subject |
| Input fields | seed (integer)<br>image (string)<br>prompt (string)<br>aspect_ratio (string; 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16)<br>output_format (string; jpeg, png)<br>guidance_scale (number; 0–20)<br>num_inference_steps (integer; 1–50) |
| Required input | prompt, image |
| Output fields | url, content_type |
| Execution | Asynchronous job |
Related Models
bfl/flux-1/dev/editbfl/flux-1/dev/image-to-imagebfl/flux-1/dev