Image Generation

Generate images from text prompts or source images using any supported model. Supports both synchronous (wait for result) and asynchronous (poll for result) processing modes.

Image Generation API

Endpoint: POST /api/v1/images/generate

Headers

Name	Value
Content-Type	application/json
Authorization	Bearer <token>

Quick Start

curl -X POST https://api.platform.qolaba.ai/api/v1/images/generate \
  -H "X-API-Key: your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "vertex/nano-banana-flash",
    "prompt": "A photorealistic cat sitting on the Eiffel Tower at sunset",
    "aspect_ratio": "16:9"
  }'

Response 200 OK:

{
  "task_id": "task_1705312200000_abc123",
  "prompt": "A photorealistic cat sitting on the Eiffel Tower at sunset",
  "images": [
    {
      "url": "https://storage.example.com/image.png",
      "width": 1280,
      "height": 720,
      "content_type": "image/png"
    }
  ],
  "usage": {
    "images_generated": 1,
    "cost_usd": 0.03,
    "cost_credits": 6
  }
}

---

Processing Modes

The celery field controls how the request is processed.

Mode	celery	HTTP Status	Description
Synchronous (default)	false	200 OK	Waits for generation to complete and returns images directly. Best for low-latency use cases.
Asynchronous	true	202 Accepted	Returns a task_id immediately. Generation happens in the background. Poll GET /api/v1/tasks/{task_id} for the result.

When to use async (celery: true):

• Generating large batches

• High-resolution images with longer generation times

• Background jobs / queue-based workflows

• Avoiding client timeout issues

---

Request Body

{
  "model": "string (required)",
  "prompt": "string",
  "celery": false
}

Core Fields

Field	Type	Required	Description
model	string	Yes	Model ID. See Supported Models.
prompt	string (max 4000)	Yes*	Text description of the image. *Optional for image-to-image models (e.g. BiRefNet).
celery	boolean	No	Processing mode. false = sync (default), true = async.

Media Inputs

Field	Type	Description
image_urls	string[]	Source image URLs for image-to-image or conversational editing.
reference_images	{ url: string, description?: string }[] (max 14)	Reference images for multi-reference consistency (character, product, or style).
mask_url	string (URL)	Black/white mask indicating the inpainting area (FLUX Inpainting only).

Size & Resolution

Field	Type	Description
aspect_ratio	string	Output aspect ratio. See valid values below. Not all models support all ratios.
quality	string	Resolution/quality preset. Model-specific values — e.g. "2K", "4K" for Vertex; "low", "medium", "high" for GPT Image 2.

Supported aspect_ratio values:

1:1  1:4  1:8  2:3  3:2  3:4  4:1  4:3  4:5  5:4  8:1  9:16  16:9  21:9

Generation Parameters

Field	Type	Range	Description
num_images	integer	1–10	Number of images to generate.
seed	integer	—	Random seed for reproducible results.
num_inference_steps	integer	1–150	Denoising steps (FAL models). More steps = higher quality, slower.
guidance_scale	number	0–30	How closely to follow the prompt (FAL models).
temperature	number	0–2	Sampling temperature for creativity (Vertex models).
negative_prompt	string (max 2000)	—	Text describing elements to exclude from the image.

---

Response Schemas

200 OK — Synchronous Result

Returned when celery: false (default). Generation is complete and images are included.

{
  "task_id": "task_1705312200000_abc123",
  "prompt": "A cat on the Eiffel Tower",
  "seed": 42,
  "images": [
    {
      "url": "https://storage.example.com/image.png",
      "width": 1024,
      "height": 1024,
      "content_type": "image/png"
    }
  ],
  "usage": {
    "images_generated": 1,
    "cost_usd": 0.025,
    "cost_credits": 7
  }
}

Field	Type	Description
task_id	string	Unique identifier for this generation task.
prompt	string	The prompt used for generation (echoed back).
seed	integer	Seed used (if applicable). Pass back to reproduce the same image.
images	ImageOutput[]	Array of generated images.
images[].url	string	Public URL of the generated image.
images[].width	integer	Image width in pixels.
images[].height	integer	Image height in pixels.
images[].content_type	string	MIME type, e.g. image/png.
usage	object	Billing information.
usage.images_generated	integer	Number of images generated.
usage.cost_usd	number	Cost in USD.
usage.cost_credits	number	Cost in platform credits (1 credit = $0.005 USD).

202 Accepted — Async Task Created

Returned when celery: true. Poll the task endpoint to retrieve the result.

{
  "task_id": "task_1705312200000_abc123",
  "status": "PENDING",
  "type": "image"
}

Field	Type	Description
task_id	string	Use this to poll GET /api/v1/tasks/{task_id}.
status	string	Initial status: always PENDING.
type	string	Always image for image generation tasks.

Error Responses

Status	error field	Description
400	Bad Request	Invalid parameters or unsupported model/field combination.
429	Rate Limited	Too many requests. See retryAfter field.
500	Internal Server Error	Unexpected server-side failure.

{
  "error": "Bad Request",
  "message": "aspect_ratio '21:9' is not supported by model 'vertex/nano-banana-pro'",
  "retryAfter": null
}

---

Code Examples

JavaScript / TypeScript

// Synchronous (default)
const response = await fetch('https://api.platform.qolaba.ai/api/v1/images/generate', {
  method: 'POST',
  headers: {
    'X-API-Key': process.env.API_KEY!,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'vertex/nano-banana-flash',
    prompt: 'A photorealistic cat sitting on the Eiffel Tower at sunset',
    aspect_ratio: '16:9',
    num_images: 1
  }),
});

const result = await response.json();
console.log(result.images[0].url);

// Asynchronous
const initRes = await fetch('https://api.platform.qolaba.ai/api/v1/images/generate', {
  method: 'POST',
  headers: { 'X-API-Key': process.env.API_KEY!, 'Content-Type': 'application/json' },
  body: JSON.stringify({
    model: 'vertex/nano-banana-flash',
    prompt: 'A highly detailed oil painting of a dragon',
    celery: true,
  }),
});

const { task_id } = await initRes.json(); // 202 Accepted

// Poll until done
const result = await pollTask(task_id);

cURL

# Sync - wait for result
curl -X POST https://api.platform.qolaba.ai/api/v1/images/generate \
  -H "X-API-Key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "vertex/nano-banana-flash",
    "prompt": "A product photo of wireless headphones",
    "quality": "high",
    "background": "transparent"
  }'

# Async - fire and forget
curl -X POST https://api.platform.qolaba.ai/api/v1/images/generate \
  -H "X-API-Key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "vertex/nano-banana-flash",
    "prompt": "Ultra-detailed fantasy landscape",
    "celery": true
  }'

---

Async Polling Flow

When using celery: true, poll the task endpoint until status is SUCCESS or FAILED.

Poll Endpoint

GET /api/v1/tasks/{task_id}

Task Status Values

Status	Description
PENDING	Task is queued, not yet started.
PROCESSING	Generation is in progress.
SUCCESS	Complete. output field contains the images.
FAILED	Generation failed. See error and error_detail fields.

Polling Example

async function pollTask(taskId: string, intervalMs = 2000, timeoutMs = 300000) {
  const deadline = Date.now() + timeoutMs;

  while (Date.now() < deadline) {
    const res = await fetch(`https://api.platform.qolaba.ai/api/v1/tasks/${taskId}`, {
      headers: { 'X-API-Key': process.env.API_KEY! },
    });
    const task = await res.json();

    if (task.status === 'SUCCESS') {
      return task.output; // ImageGenerationResponse
    }

    if (task.status === 'FAILED') {
      throw new Error(`Task failed: ${task.error_detail?.message ?? task.error}`);
    }

    await new Promise(resolve => setTimeout(resolve, intervalMs));
  }

  throw new Error('Task polling timed out');
}

Task Response Shape

{
  "task_id": "task_1705312200000_abc123",
  "status": "SUCCESS",
  "type": "image",
  "output": {
    "images": [{ "url": "...", "width": 1024, "height": 1024 }],
    "prompt": "...",
    "usage": { "images_generated": 1, "cost_usd": 0.06, "cost_credits": 12 }
  },
  "time_required_ms": 8543,
  "logs": [
    { "timestamp": "2024-01-15T10:30:00Z", "message": "Processing started" },
    { "timestamp": "2024-01-15T10:30:08Z", "message": "Generation complete" }
  ]
}

---

Run the API

To test this API, please use the following link:

https://app.theneo.io/api-runner/qolaba/ml-apis/api-reference/text-to-image-copyapp.theneo.io