Image Generation

OpenRouter supports image generation through models that have "image" in their output_modalities. These models can create images from text prompts when you specify the appropriate modalities in your request.

Model Discovery

You can find image generation models in several ways:

On the Models Page

Visit the Models page and filter by output modalities to find models capable of image generation. Look for models that list "image" in their output modalities.

In the Chatroom

When using the Chatroom, click the Image button to automatically filter and select models with image generation capabilities. If no image-capable model is active, you’ll be prompted to add one.

API Usage

To generate images, send a request to the /api/v1/chat/completions endpoint with the modalities parameter set to include both "image" and "text".

Basic Image Generation

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import { OpenRouter } from '@openrouter/sdk';
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const openRouter = new OpenRouter({
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  apiKey: '{{API_KEY_REF}}',
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});
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const result = await openRouter.chat.send({
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  model: '{{MODEL}}',
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  messages: [
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    {
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      role: 'user',
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      content: 'Generate a beautiful sunset over mountains',
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    },
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  ],
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  modalities: ['image', 'text'],
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  stream: false,
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});
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// The generated image will be in the assistant message
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if (result.choices) {
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  const message = result.choices[0].message;
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  if (message.images) {
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    message.images.forEach((image, index) => {
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      const imageUrl = image.imageUrl.url; // Base64 data URL
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      console.log(`Generated image ${index + 1}: ${imageUrl.substring(0, 50)}...`);
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    });
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  }
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}

Image Configuration Options

Some image generation models support additional configuration through the image_config parameter.

Aspect Ratio

Set image_config.aspect_ratio to request specific aspect ratios for generated images.

Supported aspect ratios:

• 1:1 → 1024×1024 (default)
• 2:3 → 832×1248
• 3:2 → 1248×832
• 3:4 → 864×1184
• 4:3 → 1184×864
• 4:5 → 896×1152
• 5:4 → 1152×896
• 9:16 → 768×1344
• 16:9 → 1344×768
• 21:9 → 1536×672

Image Size

Set image_config.image_size to control the resolution of generated images.

Supported sizes:

• 1K → Standard resolution (default)
• 2K → Higher resolution
• 4K → Highest resolution

You can combine both aspect_ratio and image_size in the same request:

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import requests
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import json
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url = "https://openrouter.ai/api/v1/chat/completions"
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headers = {
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    "Authorization": f"Bearer {API_KEY_REF}",
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    "Content-Type": "application/json"
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}
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payload = {
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    "model": "{{MODEL}}",
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    "messages": [
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        {
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            "role": "user",
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            "content": "Create a picture of a nano banana dish in a fancy restaurant with a Gemini theme"
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        }
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    ],
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    "modalities": ["image", "text"],
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    "image_config": {
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        "aspect_ratio": "16:9",
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        "image_size": "4K"
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    }
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}
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response = requests.post(url, headers=headers, json=payload)
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result = response.json()
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if result.get("choices"):
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    message = result["choices"][0]["message"]
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    if message.get("images"):
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        for image in message["images"]:
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            image_url = image["image_url"]["url"]
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            print(f"Generated image: {image_url[:50]}...")

Font Inputs (Sourceful only)

Use image_config.font_inputs to render custom text with specific fonts in generated images. The text you want to render must also be included in your prompt for best results. This parameter is only supported by Sourceful models (sourceful/riverflow-v2-fast and sourceful/riverflow-v2-pro).

Each font input is an object with:

• font_url (required): URL to the font file
• text (required): Text to render with the font

Limits:

• Maximum 2 font inputs per request
• Additional cost: $0.03 per font input

Example:

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{
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  "image_config": {
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    "font_inputs": [
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      {
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        "font_url": "https://example.com/fonts/custom-font.ttf",
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        "text": "Hello World"
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      }
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    ]
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  }
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}

Tips for best results:

• Include the text in your prompt along with details about font name, color, size, and position
• The text parameter should match exactly what’s in your prompt - avoid extra wording or quotation marks
• Use line breaks or double spaces to separate headlines and sub-headers when using the same font
• Works best with short, clear headlines and sub-headlines

Super Resolution References (Sourceful only)

Use image_config.super_resolution_references to enhance low-quality elements in your input image using high-quality reference images. The output image will match the size of your input image, so use larger input images for better results. This parameter is only supported by Sourceful models (sourceful/riverflow-v2-fast and sourceful/riverflow-v2-pro) when using image-to-image generation (i.e., when input images are provided in messages).

Limits:

• Maximum 4 reference URLs per request
• Only works with image-to-image requests (ignored when there are no images in messages)
• Additional cost: $0.20 per reference

Example:

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{
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  "image_config": {
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    "super_resolution_references": [
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      "https://example.com/reference1.jpg",
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      "https://example.com/reference2.jpg"
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    ]
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  }
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}

Tips for best results:

• Supply an input image where the elements to enhance are present but low quality
• Use larger input images for better output quality (output matches input size)
• Use high-quality reference images that show what you want the enhanced elements to look like

Streaming Image Generation

Image generation also works with streaming responses:

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import requests
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import json
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url = "https://openrouter.ai/api/v1/chat/completions"
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headers = {
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    "Authorization": f"Bearer {API_KEY_REF}",
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    "Content-Type": "application/json"
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}
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payload = {
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    "model": "{{MODEL}}",
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    "messages": [
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        {
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            "role": "user",
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            "content": "Create an image of a futuristic city"
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        }
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    ],
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    "modalities": ["image", "text"],
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    "stream": True
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}
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response = requests.post(url, headers=headers, json=payload, stream=True)
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for line in response.iter_lines():
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    if line:
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        line = line.decode('utf-8')
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        if line.startswith('data: '):
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            data = line[6:]
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            if data != '[DONE]':
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                try:
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                    chunk = json.loads(data)
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                    if chunk.get("choices"):
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                        delta = chunk["choices"][0].get("delta", {})
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                        if delta.get("images"):
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                            for image in delta["images"]:
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                                print(f"Generated image: {image['image_url']['url'][:50]}...")
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                except json.JSONDecodeError:
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                    continue

Response Format

When generating images, the assistant message includes an images field containing the generated images:

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{
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  "choices": [
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    {
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      "message": {
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        "role": "assistant",
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        "content": "I've generated a beautiful sunset image for you.",
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        "images": [
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          {
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            "type": "image_url",
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            "image_url": {
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              "url": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA..."
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            }
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          }
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        ]
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      }
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    }
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  ]
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}

Image Format

• Format: Images are returned as base64-encoded data URLs
• Types: Typically PNG format (data:image/png;base64,)
• Multiple Images: Some models can generate multiple images in a single response
• Size: Image dimensions vary by model capabilities

Model Compatibility

Not all models support image generation. To use this feature:

1. Check Output Modalities: Ensure the model has "image" in its output_modalities
2. Set Modalities Parameter: Include "modalities": ["image", "text"] in your request
3. Use Compatible Models: Examples include:
   • google/gemini-2.5-flash-image-preview
   • black-forest-labs/flux.2-pro
   • black-forest-labs/flux.2-flex
   • sourceful/riverflow-v2-standard-preview
   • Other models with image generation capabilities

Best Practices

• Clear Prompts: Provide detailed descriptions for better image quality
• Model Selection: Choose models specifically designed for image generation
• Error Handling: Check for the images field in responses before processing
• Rate Limits: Image generation may have different rate limits than text generation
• Storage: Consider how you’ll handle and store the base64 image data

Troubleshooting

No images in response?

• Verify the model supports image generation (output_modalities includes "image")
• Ensure you’ve included "modalities": ["image", "text"] in your request
• Check that your prompt is requesting image generation

Model not found?

• Use the Models page to find available image generation models
• Filter by output modalities to see compatible models