# Imagen 4 Fast

> Generate high-quality, photorealistic images from a text prompt fast and at the best price, with strong prompt adherence and improved in-image text rendering.

## Overview

- **Endpoint**: `https://queue.modelrunner.run/google/imagen4/fast`
- **Model ID**: `google/imagen4/fast`
- **Category**: text-to-image
- **Kind**: inference
- **Tags**: imagen, imagen4, imagen-4, fast, google, text-to-image, image-generation, photorealistic, text-rendering

## Pricing

- **Price**: $0.02 per output

## Request Lifecycle

This model runs on the ModelRunner **asynchronous queue API** — a single POST does not return the output. Every call requires an `Authorization: Key $MODEL_RUNNER_KEY` header. Run three steps:

1. **Submit** — `POST https://queue.modelrunner.run/google/imagen4/fast` with a JSON body holding the input fields at the top level. The body may also include a reserved top-level `metadata` object — a flat string map (max 16 keys, key ≤64 / value ≤512 chars) stored on the request for your own tagging. It is never sent to the model; filter your request history with `GET https://queue.modelrunner.run/requests?metadata=<url-encoded JSON>` (exact key=value matches, AND-ed). The response carries request handles only (no output yet):

```json
{
  "status": "IN_QUEUE",
  "request_id": "<21-char id>",
  "status_url": "https://queue.modelrunner.run/google/imagen4/fast/requests/<request_id>/status",
  "response_url": "https://queue.modelrunner.run/google/imagen4/fast/requests/<request_id>",
  "cancel_url": "https://queue.modelrunner.run/google/imagen4/fast/requests/<request_id>/cancel"
}
```

2. **Poll status** — `GET <status_url>` until `status` is `COMPLETED`. Possible values are `IN_QUEUE`, `IN_PROGRESS`, `COMPLETED`, `FAILED`, `CANCELLED`. A `FAILED` request responds with HTTP 400 and an `error` field.

3. **Read result** — `GET <response_url>`. Returns the finished request, including the generated `output`:

```json
{ "id": "<request_id>", "status": "COMPLETED", "output": ..., "input": ... }
```

The JavaScript and Python SDKs below perform steps 2–3 for you. In any language without an SDK (Swift, Go, Kotlin, etc.) you must implement the polling loop and the final result fetch yourself — see the cURL example for the full flow.

### Input Schema

- **`seed`** (`integer | null`, _optional_):
  Seed for reproducible generation. Leave unset for a random result.

- **`prompt`** (`string`, _required_):
  Text description of the image to generate.

- **`num_images`** (`integer`, _optional_):
  The number of images to generate. Each generated image is billed.
  - Default: `1`
  - Range: `1` to `4`

- **`aspect_ratio`** (`AspectRatioEnum`, _optional_):
  The aspect ratio of the generated image.
  - Default: `"1:1"`
  - Options: `"1:1"`, `"16:9"`, `"9:16"`, `"4:3"`, `"3:4"`

- **`output_format`** (`OutputFormatEnum`, _optional_):
  The file format of the generated image.
  - Default: `"png"`
  - Options: `"jpeg"`, `"png"`, `"webp"`

- **`safety_tolerance`** (`SafetyToleranceEnum`, _optional_):
  Content moderation strictness from 1 (strictest) to 6 (most permissive).
  - Default: `"4"`
  - Options: `"1"`, `"2"`, `"3"`, `"4"`, `"5"`, `"6"`

### Output Schema

_No `Output` schema properties are available._

## Default Example

**Input**

```json
{
  "prompt": "a steaming espresso cup on a rustic wooden table in a cozy Italian cafe, warm afternoon sunlight streaming through a frosted window, 9:16 portrait",
  "aspect_ratio": "9:16",
  "output_format": "png",
  "safety_tolerance": "4"
}
```

**Output**

```json
[
  "https://media.modelrunner.ai/H4EP7sRBBrzLbD2zDGuBh.png"
]
```
## Usage Examples

### cURL

The queue API is asynchronous: submit the request, poll `status_url` until it is `COMPLETED`, then read the result from `response_url`. Requires `jq`.

```bash
# 1. Submit the request (returns request handles, not the output)
SUBMIT=$(curl --silent --request POST \
  --url https://queue.modelrunner.run/google/imagen4/fast \
  --header "Authorization: Key $MODEL_RUNNER_KEY" \
  --header "Content-Type: application/json" \
  --data '{
  "prompt": "a steaming espresso cup on a rustic wooden table in a cozy Italian cafe, warm afternoon sunlight streaming through a frosted window, 9:16 portrait",
  "aspect_ratio": "9:16",
  "output_format": "png",
  "safety_tolerance": "4"
}')

STATUS_URL=$(echo "$SUBMIT" | jq -r '.status_url')
RESPONSE_URL=$(echo "$SUBMIT" | jq -r '.response_url')

# 2. Poll until the request leaves the queue / in-progress state
while true; do
  STATUS=$(curl --silent --url "$STATUS_URL" \
    --header "Authorization: Key $MODEL_RUNNER_KEY" | jq -r '.status')
  echo "Status: $STATUS"
  case "$STATUS" in
    COMPLETED) break ;;
    FAILED|CANCELLED) echo "Request $STATUS"; exit 1 ;;
  esac
  sleep 1
done

# 3. Read the finished request, including the generated output
curl --silent --url "$RESPONSE_URL" \
  --header "Authorization: Key $MODEL_RUNNER_KEY"
```

### JavaScript

```javascript
import { modelrunner } from "@modelrunner/client";

const result = await modelrunner.subscribe("google/imagen4/fast", {
  input: {
  "prompt": "a steaming espresso cup on a rustic wooden table in a cozy Italian cafe, warm afternoon sunlight streaming through a frosted window, 9:16 portrait",
  "aspect_ratio": "9:16",
  "output_format": "png",
  "safety_tolerance": "4"
}
});

console.log(result.data);
```

### Python

```python
import asyncio
import modelrunner_ai

async def main():
    response = await modelrunner_ai.submit_async(
        "google/imagen4/fast",
        arguments={
  "prompt": "a steaming espresso cup on a rustic wooden table in a cozy Italian cafe, warm afternoon sunlight streaming through a frosted window, 9:16 portrait",
  "aspect_ratio": "9:16",
  "output_format": "png",
  "safety_tolerance": "4"
}
    )
    result = await response.get()
    print(result["output"])

asyncio.run(main())
```

## Additional Resources

- [Playground](https://modelrunner.ai/models/google/imagen4/fast)
- [OpenAPI Schema](https://modelrunner.ai/models/google/imagen4/fast/openapi.json)
- [LLM Instructions](https://modelrunner.ai/models/google/imagen4/fast/llms.txt)