generate-image

Generate images using Google's Nano Banana Pro (Gemini 3 Pro Image) model.

When to Use This Skill

Use this skill when...	Use imagemagick-conversion instead when...
Producing a brand-new image from a text prompt	Converting, resizing, or compressing an existing image
Generating cinematic, product, or portrait artwork	Building thumbnails or batch-processing many files
Mixing up to five reference images into a new render	Applying deterministic transforms (rotate, crop, format)

Use this skill when...	Use mermaid-diagrams or d2-diagrams instead when...
The output is a photographic or illustrative image	The output is a flowchart, sequence, or architecture diagram
Quality settings (1K/2K/4K) and aspect ratio matter	Diagram-as-code rendering would be more maintainable

Parameters

Parse these from $ARGUMENTS. The prompt is the quoted string (or, if unquoted, every token before the first -- flag):

• prompt (required): Image description. If $ARGUMENTS is empty, ask the user for one and stop.
• --aspect: Aspect ratio (1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9) - default: 16:9
• --resolution: Image resolution (1K, 2K, 4K) - default: 2K
• --reference: Path to reference image (repeatable, max 5)
• --output: Custom output path

Environment Requirements

Verify API key is set:

echo "API Key: ${GOOGLE_API_KEY:+SET}${GEMINI_API_KEY:+SET}"

If not set, get one from: https://aistudio.google.com/apikey

Usage Examples

/generate-image "A beautiful mountain landscape at sunset"
/generate-image "Product photo on white background" --aspect 1:1 --resolution 4K
/generate-image "Portrait photo" --aspect 3:4
/generate-image "Cinematic scene" --aspect 21:9
/generate-image "Similar style" --reference existing_image.png

Task Workflow

1. Parse arguments from $ARGUMENTS (see Parameters):

   • Extract the prompt
   • Read --aspect (default 16:9), --resolution (default 2K), each --reference <path> (at most 5), and --output <path> if given

2. Build and execute the command, substituting the parsed values for the <...> slots. Add one --reference <path> per reference image and --output <path> only when given:

   uv run python .claude/scripts/nano_banana_pro.py "<prompt>" \
     --aspect <ratio> \
     --resolution <size> \
     --reference <path>
   

3. Report results:

   • Show path to generated image
   • Note any reference images used
   • Offer next steps (regenerate, different aspect, etc.)

Output

Default output: ./generated/image_YYYYMMDD_HHMMSS.png

Custom output with --output:

/generate-image "Scene" --output custom_name.png

Reference Images

Reference images help maintain consistency:

• Use existing images as style references
• Keep subjects consistent across generations
• Match artistic styles

When using references, describe the relationship:

• "Similar style to the reference"
• "This person in a different setting"
• "Same product, different angle"

Maximum 5 reference images per generation.

Aspect Ratio Quick Reference

Use Case	Ratio
Square/Instagram	1:1
Portrait	3:4, 9:16
Landscape	16:9
Ultrawide	21:9
Photo	3:2, 4:3

Resolution Quick Reference

Use Case	Resolution
Preview	1K
Standard	2K
High quality	4K

Error Handling

• No API key: Set GOOGLE_API_KEY or GEMINI_API_KEY
• Generation failed: Simplify prompt or reduce references
• Rate limited: Wait and retry