Promptgen Command

Transform simple descriptions into detailed, optimized image generation prompts using Gemini 2.0 Flash AI.

Usage

gemini-nano-banana-tool promptgen DESCRIPTION [OPTIONS]

Arguments

• DESCRIPTION - Simple description to enhance (e.g., "wizard cat", "cyberpunk city")

Options

• -t, --template TEXT - Apply specialized template (photography, character, scene, food, abstract, logo)
• -s, --style TEXT - Style hint (photorealistic, artistic, minimalist, etc.)
• -o, --output PATH - Save prompt to file instead of stdout
• --json - Output in JSON format
• -v, --verbose - Show analysis and reasoning
• --list-templates - Show all available templates

Examples

Basic Usage

# Generate detailed prompt from simple description
gemini-nano-banana-tool promptgen "wizard cat"

# With template for better results
gemini-nano-banana-tool promptgen "wizard cat" --template character

# Save to file for reuse
gemini-nano-banana-tool promptgen "sunset landscape" -o prompt.txt

Pipeline: Generate Prompt → Create Image

# Single pipeline: description → optimized prompt → image
gemini-nano-banana-tool promptgen "wizard cat in magical library" | \
  gemini-nano-banana-tool generate --stdin -o wizard-cat.png -a 16:9

With Templates

# Photography template - technical camera details
gemini-nano-banana-tool promptgen "mountain landscape" --template photography

# Food template - plating and lighting
gemini-nano-banana-tool promptgen "pasta dish" --template food

# Scene template - foreground/midground/background
gemini-nano-banana-tool promptgen "cyberpunk city" --template scene

JSON Output (for automation)

# Get structured output
gemini-nano-banana-tool promptgen "sunset" --json

# Output format:
# {
#   "original": "sunset",
#   "prompt": "A breathtaking golden hour sunset...",
#   "template": null,
#   "style": null,
#   "tokens_used": 156
# }

Available Templates

• photography - Professional photography with technical details (aperture, focal length, lighting)
• character - Character design with pose, attire, expression
• scene - Scene composition with foreground/midground/background layers
• food - Food photography with plating, garnish, lighting
• abstract - Abstract art with shapes, colors, patterns
• logo - Logo design with typography, symbolism, brand identity

Why Use Promptgen?

Creating effective image generation prompts requires knowledge of:

• Photography and composition terminology
• Lighting and technical details
• Artistic styles and techniques
• Color theory and palettes

Promptgen automates this expertise using AI, transforming simple ideas into detailed, effective prompts.

Output Modes

• Plain text (default) - Ready for piping to generate command
• JSON (--json) - Structured output for scripts and automation
• Verbose (-v) - Shows AI analysis and reasoning process

Cost

Promptgen uses Gemini 2.0 Flash for prompt generation:

• Cost: ~$0.001-0.003 per prompt optimization
• Much cheaper than trial-and-error generation

Authentication

Requires GEMINI_API_KEY or GOOGLE_API_KEY environment variable.

Get your API key: https://aistudio.google.com/app/apikey