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

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