Nano Banana Poster Generator

Nano Banana Poster Generator

Generate images using Google's Gemini model with optional reference assets.

Quick Start

cd ~/​.claude/​skills/​nano-banana-image/​scripts

# Basic generation (default 3:2 horizontal)
npx ts-node generate_poster.ts "A futuristic city at sunset"

# With aspect ratio (3:2 horizontal, 2:3 vertical, 16:9 wide, 9:16 tall)
npx ts-node generate_poster.ts --aspect 3:2 "A wide landscape poster"
npx ts-node generate_poster.ts -a 9:16 "A vertical story format"

# With reference assets
npx ts-node generate_poster.ts --assets "my-logo" "Create banner with logo"

# Combined: aspect ratio + assets
npx ts-node generate_poster.ts --aspect 16:9 --assets "logo" "YouTube thumbnail"

Aspect Ratio

IMPORTANT: Always use the default 3:2 aspect ratio unless the user explicitly requests a different format (like "vertical", "story", "square", etc.). Do NOT change the aspect ratio on your own.

Control image dimensions with --aspect or -a:

npx ts-node generate_poster.ts --aspect 3:2 "Your prompt"
npx ts-node generate_poster.ts -a 16:9 "Your prompt"

Adding Assets

Use --assets with full paths to include reference images:

# Single asset
npx ts-node generate_poster.ts --assets "/​full/​path/​to/​image.jpg" "Your prompt"

# Multiple assets (comma-separated)
npx ts-node generate_poster.ts --assets "/​path/​a.jpg,/​path/​b.png" "Use both images"

Supported formats: .jpg, .jpeg, .png, .webp, .gif

IMPORTANT: Assets are NOT automatically included. You must explicitly pass them via --assets.

Save to Gallery

Save good results for future style reference:

npx ts-node generate_poster.ts --save-to-gallery "my-style" "prompt"

Creates assets/​gallery/​my-style.jpg + .meta.json with prompt info.

API Configuration

Create scripts/​.env:

GEMINI_API_KEY=your_api_key_here

Hebrew/​RTL Content

When generating images with Hebrew text:

ALWAYS include in prompt:

CRITICAL: All text must be in Hebrew.
CRITICAL: Layout direction is RTL (right-to-left).
Flow, reading order, and visual hierarchy must go from RIGHT to LEFT.

This ensures text renders correctly and visual flow matches Hebrew reading direction.

Output

• Files saved as poster_0.jpg, poster_1.jpg, etc.
• Aspect ratio: Configurable via --aspect (default: 3:2)
• Quality: 1K (1024px on longest edge)