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:

Look for a .env file in the project directory or parent directories
Check for OPENROUTER_API_KEY=<key> in the .env file
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-flex - Fast and cheap, but not as high quality as pro

Select based on:

Quality: Use gemini-3-pro or flux.2-flex
Editing: Use gemini-3-pro or flux.2-flex (both support image editing)
Cost: Use flux.2-flex 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