Nano Image Generator

Generate images using Nano Banana Pro (Gemini 3 Pro Preview) for any visual asset needs. Supports reference images for style transfer and character consistency.

Quick Start

bash
1# Basic generation
2python scripts/generate_image.py "A friendly robot mascot waving" --output ./mascot.png
3
4# With style reference (keep same visual style)
5python scripts/generate_image.py "Same style, new content" --ref ./reference.jpg --output ./new.png

Script Usage

bash
1python scripts/generate_image.py <prompt> --output <path> [options]

Required:

• prompt - Image description
• --output, -o - Output file path

Options:

• --aspect, -a - Aspect ratio (default: 1:1)
  • Square: 1:1
  • Portrait: 2:3, 3:4, 4:5, 9:16
  • Landscape: 3:2, 4:3, 5:4, 16:9, 21:9
• --size, -s - Resolution: 1K, 2K (default), 4K
• --ref, -r - Reference image (can use multiple times, max 14)

Reference Images

Gemini supports up to 14 reference images for:

Style Transfer

Keep the visual style (colors, textures, mood) from a reference:

bash
1python scripts/generate_image.py "New scene with mountains, same visual style as reference" \
2  --ref ./style-reference.jpg --output ./styled-mountains.png

Character Consistency

Maintain character appearance across multiple images:

bash
1python scripts/generate_image.py "Same character now in a forest setting" \
2  --ref ./character.png --output ./character-forest.png

Multi-Image Fusion

Combine elements from multiple references:

bash
1python scripts/generate_image.py "Combine the style of first image with subject of second" \
2  --ref ./style.png --ref ./subject.png --output ./combined.png

Serial Image Generation (Batch Workflow)

For generating a series with consistent style:

1. Generate first image
2. Use first image as --ref for subsequent images
3. Each new image inherits the established style

bash
1# Generate cover
2python scripts/generate_image.py "Tech knowledge card cover" -o ./01-cover.png
3
4# Generate subsequent cards with style reference
5python scripts/generate_image.py "Card 2 content, same style" --ref ./01-cover.png -o ./02-card.png
6python scripts/generate_image.py "Card 3 content, same style" --ref ./01-cover.png -o ./03-card.png

Workflow

1. Determine output location - Place images where contextually appropriate:

   • App icons → ./assets/icons/
   • Marketing → ./marketing/
   • UI elements → ./src/assets/
   • General → ./generated/

2. Craft effective prompts - Be specific and descriptive:

   • Include style: "flat design", "3D rendered", "watercolor", "minimalist"
   • Include context: "for a mobile app", "website hero image"
   • Include details: colors, mood, composition
   • For references: mention "same style as reference" or "keep the visual style"

3. Choose appropriate settings:

   • Icons/logos → --aspect 1:1
   • Banners/headers → --aspect 16:9 or 21:9
   • Mobile screens → --aspect 9:16
   • Xiaohongshu cards → --aspect 3:4
   • Photos → --aspect 3:2 or 4:3

Examples

App icon:

bash
1python scripts/generate_image.py "Minimalist flat design app icon of a lightning bolt, purple gradient background, modern iOS style" \
2  --output ./assets/app-icon.png --aspect 1:1

Marketing banner:

bash
1python scripts/generate_image.py "Professional website hero banner for a productivity app, abstract geometric shapes, blue and white color scheme" \
2  --output ./public/images/hero-banner.png --aspect 16:9

Xiaohongshu knowledge card:

bash
1python scripts/generate_image.py "Tech knowledge card, dark blue purple gradient, neon cyan accents, code block style, Chinese text '标题'" \
2  --output ./xiaohongshu/card.png --aspect 3:4

Style transfer:

bash
1python scripts/generate_image.py "Transform this photo into watercolor painting style" \
2  --ref ./photo.jpg --output ./watercolor.png

Character in new scene:

bash
1python scripts/generate_image.py "Same character from reference, now sitting in a cafe, warm lighting" \
2  --ref ./character.png --output ./character-cafe.png --aspect 3:2

Prompt Tips

• Be specific - "A red apple on a wooden table" vs "an apple"
• Include style - "in the style of pixel art" or "photorealistic"
• Mention purpose - "for a children's book" affects the output style
• Describe composition - "centered", "rule of thirds", "close-up"
• Specify colors - Explicit color palettes yield better results
• Reference prompts - Use "same style as reference", "keep the visual aesthetic", "match the color palette"
• Avoid - Don't ask for complex text in images (use overlays instead)

Limitations

• Maximum 14 reference images per request
• Text rendering may be imperfect (better to overlay text separately)
• Very specific brand logos may not reproduce exactly