image-gen

name	image-gen
description	Generate images using Google's Nano Banana 2 (Gemini 3.1 Flash Image) with workflow-based prompting
triggers	["create image","generate image","make infographic","create infographic","generate diagram","make diagram","design visual","create visual"]
allowed-tools	Read, Write, Bash
version	0.1.0

Image Generation Skill

Generate professional images, infographics, and diagrams using Google's Nano Banana 2 model (gemini-3.1-flash-image-preview).

Model Capabilities

Nano Banana 2 (released February 26, 2026):

• Text rendering - Accurate, legible text in images
• Google Search grounding - Real-time data (weather, stocks, etc.)
• Subject consistency - Up to 5 characters maintained across generations
• Multi-turn conversation - Iterative refinement
• Up to 14 reference images - For composition and style transfer
• Resolutions: 1K, 2K, 4K
• Aspect ratios: 1:1, 2:3, 3:2, 4:3, 16:9, 21:9

Scripts

All scripts use Python via uv run with inline dependencies.

generate.py - Text to Image

uv run scripts/generate.py "prompt" output.png [aspect_ratio] [size]

Examples:

# Basic image
uv run scripts/generate.py "A cozy coffee shop in autumn" coffee.png

# Infographic with specific aspect ratio
uv run scripts/generate.py "Infographic explaining how neural networks work" nn.png 16:9 2K

# 4K professional image
uv run scripts/generate.py "Professional headshot, studio lighting" headshot.png 3:2 4K

edit.py - Image Editing

uv run scripts/edit.py input.png "edit instructions" output.png

Examples:

# Edit existing image
uv run scripts/edit.py photo.png "Change the background to a beach sunset" edited.png

compose.py - Multi-Image Composition

uv run scripts/compose.py "prompt" output.png --refs image1.png image2.png

Examples:

# Combine styles from multiple images
uv run scripts/compose.py "Combine these styles into a logo" logo.png --refs style1.png style2.png

Workflows

Workflows provide structured approaches for specific visual types. Each workflow follows the PAI 6-step editorial process:

1. Extract narrative - Understand the complete story/concept
2. Derive visual concept - Single metaphor with 2-3 physical objects
3. Apply aesthetic - Define style, colors, mood
4. Construct prompt - Build detailed generation instructions
5. Generate - Execute via script
6. Validate - Check against criteria, regenerate if needed

Available Workflows

• infographic.md - Data visualization, statistics, explainers
• diagram.md - Technical diagrams, flowcharts, architecture

Workflow Usage

When generating images, follow the appropriate workflow:

For Infographics

1. What data/concept needs visualization?
2. What's the key insight or takeaway?
3. Aspect ratio: 16:9 (landscape) recommended
4. Include: clear hierarchy, minimal text, supporting icons
5. Generate at 2K minimum for text clarity

For Diagrams

1. What system/process is being illustrated?
2. What are the key components and relationships?
3. Style: flat colors, clean lines, minimal detail
4. Generate at 2K for label clarity

Environment Setup

Requires GEMINI_API_KEY environment variable. This should be set from Geoffrey's secrets:

source ~/Library/Mobile\ Documents/com~apple~CloudDocs/Geoffrey/secrets/.env

Best Practices

Infographics

• Use simple, direct prompts: "Infographic explaining how X works"
• Model auto-includes relevant icons/logos
• 16:9 aspect ratio works best
• Generate at 2K+ for readable text

General

• Multi-turn refinement: generate, then ask for specific changes
• Reference images improve consistency
• Be specific about style, mood, lighting
• SynthID watermark is automatic (Google provenance)

Output Location

By default, save images to /tmp/ or user-specified paths. For persistent storage, use:

~/Library/Mobile Documents/com~apple~CloudDocs/Geoffrey/images/

⚠️ CRITICAL: Never Read Generated Images

DO NOT use the Read tool on generated images.

Why:

• 4K images (3840x2160) are within the 8000px limit
• 2K images (2560x1440) are also safe
• BUT: Do not Read them - they're for user consumption, not analysis
• For edits, use edit.py script, not Read tool

Workflow:

1. Generate image with script
2. Return file path to user
3. User views the high-quality output

Limitations

• No photorealistic humans (safety filter)
• No copyrighted characters
• Maximum 14 reference images for composition
• 4K only available with Nano Banana 2 and Nano Banana Pro

Pricing

Size	Cost per Image
1K	Free tier / $0.04
2K	$0.134
4K	$0.24