Generate Image

Generate Image

Generate and edit high-quality images using OpenRouter's image generation models including Gemini 3 Pro Image and GPT-5 Image.

When to Use This Skill

Use generate-image for:

• Photos and photorealistic images
• Artistic illustrations and artwork
• Concept art and visual concepts
• Visual assets for presentations or documents
• Image editing and modifications
• Any general-purpose image generation needs

Use scientific-schematics instead for:

• Flowcharts and process diagrams
• Circuit diagrams and electrical schematics
• Biological pathways and signaling cascades
• System architecture diagrams
• CONSORT diagrams and methodology flowcharts
• Any technical/schematic diagrams

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

The script requires an OpenRouter API key and resolves it in this order:

1. --api-key
2. the OPENROUTER_API_KEY environment variable
3. OPENROUTER_API_KEY= in a .env file, searching the working directory upward

Do not open the .env file to check for the key -- run the script and read its exit status. With no key it exits with setup instructions. Keys: https://openrouter.ai/keys

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
• google/gemini-3-pro-image - Same model, non-preview id
• google/gemini-3.1-flash-image - Roughly half the per-image cost of gemini-3-pro
• openai/gpt-5-image-mini - Cheapest of these per generated image

Select based on:

• Quality: Use gemini-3-pro-image-preview or gemini-3-pro-image
• Editing: All four accept an input image
• Cost: Use gemini-3.1-flash-image or gpt-5-image-mini

The script posts to /api/v1/chat/completions, so a model works only if it is listed at https://openrouter.ai/api/v1/models with image in its architecture.output_modalities. The Flux.2 ids are served by OpenRouter's separate Images API (/api/v1/images/models) and fail here.

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 "google/gemini-3.1-flash-image"

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 "google/gemini-3.1-flash-image"

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 the environment and .env file)

Example Use Cases

For Scientific Documents

# Generate a conceptual illustration for a paper
python scripts/generate_image.py "Microscopic view of cancer cells being attacked by immunotherapy agents, scientific illustration style" --output figures/immunotherapy_concept.png

# Create a visual for a presentation
python scripts/generate_image.py "DNA double helix structure with highlighted mutation site, modern scientific visualization" --output slides/dna_mutation.png

For Presentations and Posters

# Title slide background
python scripts/generate_image.py "Abstract blue and white background with subtle molecular patterns, professional presentation style" --output slides/background.png

# Poster hero image
python scripts/generate_image.py "Laboratory setting with modern equipment, photorealistic, well-lit" --output poster/hero.png

For General Visual Content

# Website or documentation images
python scripts/generate_image.py "Professional team collaboration around a digital whiteboard, modern office" --output docs/team_collaboration.png

# Marketing materials
python scripts/generate_image.py "Futuristic AI brain concept with glowing neural networks" --output marketing/ai_concept.png

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.

Critical Prompt Requirements

IMPORTANT: No Meta Instructions in Output

When generating prompts for the AI image generation models, ensure the generated image does NOT contain any visible text showing:

• The prompt or instructions that were given to generate it
• System instructions or AI-related metadata
• Any "meta" text describing how the image was created
• Watermarks or labels indicating AI generation
• Layout descriptions (e.g., "left panel", "right panel", "center panel")
• Font specifications or typography instructions
• Color scheme descriptions or palette information

The image should only contain the requested visual content. Always include this instruction in your prompts: "Do not include any text showing the prompt, instructions, layout descriptions, font/color specifications, or metadata in the generated image."

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
• Every model listed under Model Selection supports image editing through OpenRouter

Integration with Other Skills

• scientific-schematics: Use for technical diagrams, flowcharts, circuits, pathways
• generate-image: Use for photos, illustrations, artwork, visual concepts
• scientific-slides: Combine with generate-image for visually rich presentations
• latex-posters: Use generate-image for poster visuals and hero images