generate-image

Generate Image

Generate and edit high-quality images using OpenRouter's image generation models including FLUX.2 Pro and Nano Banana Pro (Gemini 3 Pro).

Quick Start

Use the scripts/generate_image.py script to generate or edit images:

# Generate a new image
python scripts/generate_image.py "A beautiful sunset over mountains"

# Edit an existing image
python scripts/generate_image.py "Make the sky purple" --input photo.jpg

This generates/edits an image and saves it as generated_image.png in the current directory.

API Key Setup

CRITICAL: The script requires an OpenRouter API key. Before running, check if the user has configured their API key:

1. Look for a .env file in the project directory or parent directories
2. Check for OPENROUTER_API_KEY=<key> in the .env file
3. If not found, inform the user they need to:

• Create a .env file with OPENROUTER_API_KEY=your-api-key-here
• Or set the environment variable: export OPENROUTER_API_KEY=your-api-key-here
• Get an API key from: https://openrouter.ai/keys

The script will automatically detect the .env file and provide clear error messages if the API key is missing.

Model Selection

Default model: google/gemini-3-pro-image-preview (high quality, recommended)

Available models for generation and editing:

• google/gemini-3-pro-image-preview - High quality, supports generation + editing
• black-forest-labs/flux.2-pro - Fast, high quality, supports generation + editing

Generation only:

• black-forest-labs/flux.2-dev - Development version, generation only

Select based on:

• Quality: Use gemini-3-pro or flux.2-pro
• Editing: Use gemini-3-pro or flux.2-pro (both support image editing)
• Cost: Use flux.2-dev for generation only

Common Usage Patterns

Basic generation

python scripts/generate_image.py "Your prompt here"

Specify model

python scripts/generate_image.py "A cat in space" --model "black-forest-labs/flux.2-pro"

Custom output path

python scripts/generate_image.py "Abstract art" --output artwork.png

Edit an existing image

python scripts/generate_image.py "Make the background blue" --input photo.jpg

Edit with a specific model

python scripts/generate_image.py "Add sunglasses to the person" --input portrait.png --model "black-forest-labs/flux.2-pro"

Edit with custom output

python scripts/generate_image.py "Remove the text from the image" --input screenshot.png --output cleaned.png

Multiple images

Run the script multiple times with different prompts or output paths:

python scripts/generate_image.py "Image 1 description" --output image1.png
python scripts/generate_image.py "Image 2 description" --output image2.png

Script Parameters

• prompt (required): Text description of the image to generate, or editing instructions
• --input or -i: Input image path for editing (enables edit mode)
• --model or -m: OpenRouter model ID (default: google/gemini-3-pro-image-preview)
• --output or -o: Output file path (default: generated_image.png)
• --api-key: OpenRouter API key (overrides .env file)

Error Handling

The script provides clear error messages for:

• Missing API key (with setup instructions)
• API errors (with status codes)
• Unexpected response formats
• Missing dependencies (requests library)

If the script fails, read the error message and address the issue before retrying.

Notes

• Images are returned as base64-encoded data URLs and automatically saved as PNG files
• The script supports both images and content response formats from different OpenRouter models
• Generation time varies by model (typically 5-30 seconds)
• For image editing, the input image is encoded as base64 and sent to the model
• Supported input image formats: PNG, JPEG, GIF, WebP
• Check OpenRouter pricing for cost information: https://openrouter.ai/models

Image Editing Tips

• Be specific about what changes you want (e.g., "change the sky to sunset colors" vs "edit the sky")
• Reference specific elements in the image when possible
• For best results, use clear and detailed editing instructions
• Both Gemini 3 Pro and FLUX.2 Pro support image editing through OpenRouter