nano-banana

# Nano Banana Image Generation

Generate professional images via the Gemini CLI's nanobanana extension.

## When to Use This Skill

ALWAYS use this skill when the user:
- Asks for any image, graphic, illustration, or visual
- Wants a thumbnail, featured image, or banner
- Requests icons, diagrams, or patterns
- Asks to edit, modify, or restore a photo
- Uses words like: generate, create, make, draw, design, visualize

Do NOT attempt to generate images through any other method.

## Before First Use

1. Verify extension is installed:
   ```bash
   gemini extensions list | grep nanobanana
   ```
2. If missing, install it:
   ```bash
   gemini extensions install https://github.com/gemini-cli-extensions/nanobanana
   ```
3. Verify API key is set:
   ```bash
   [ -n "$GEMINI_API_KEY" ] && echo "API key configured" || echo "Missing GEMINI_API_KEY"
   ```

## Command Selection

| User Request | Command |
|--------------|---------|
| "make me a blog header" | `/generate` |
| "create an app icon" | `/icon` |
| "draw a flowchart of..." | `/diagram` |
| "fix this old photo" | `/restore` |
| "remove the background" | `/edit` |
| "create a repeating texture" | `/pattern` |
| "make a comic strip" | `/story` |

## Available Commands

**Note:** Always use the `--yolo` flag to automatically approve all tool actions.

| Command | Use Case |
|---------|----------|
| `gemini --yolo "/generate 'prompt'"` | Text-to-image generation |
| `gemini --yolo "/edit file.png 'instruction'"` | Modify existing image |
| `gemini --yolo "/restore old_photo.jpg 'fix scratches'"` | Repair damaged photos |
| `gemini --yolo "/icon 'description'"` | App icons, favicons, UI elements |
| `gemini --yolo "/diagram 'description'"` | Flowcharts, architecture diagrams |
| `gemini --yolo "/pattern 'description'"` | Seamless textures and patterns |
| `gemini --yolo "/story 'description'"` | Sequential/narrative images |
| `gemini --yolo "/nanobanana prompt"` | Natural language interface |

## Common Options

- `--yolo` - **Required.** Auto-approve all tool actions (no confirmation prompts)
- `--count=N` - Generate N variations (1-8)
- `--preview` - Auto-open generated images
- `--styles="style1,style2"` - Apply artistic styles
- `--format=grid|separate` - Output arrangement

## Common Sizes

| Use Case | Dimensions | Notes |
|----------|------------|-------|
| YouTube thumbnail | 1280x720 | `--aspect=16:9` |
| Blog featured image | 1200x630 | Social preview friendly |
| Square social | 1080x1080 | Instagram, LinkedIn |
| Twitter/X header | 1500x500 | Wide banner |
| Vertical story | 1080x1920 | `--aspect=9:16` |

## Model Selection

Default: `gemini-2.5-flash-image` (~$0.04/image)

For higher quality (4K, better reasoning):
```bash
export NANOBANANA_MODEL=gemini-3-pro-image-preview
```

## Blog Featured Image Examples

```bash
# Modern illustration style
gemini --yolo "/generate 'modern flat illustration of developer coding at laptop, purple and blue gradient background, minimalist style, no text' --preview"

# Professional photography style
gemini --yolo "/generate 'professional editorial photo of coffee cup next to laptop on wooden desk, morning sunlight, shallow depth of field, no text' --count=3"

# Tech/abstract
gemini --yolo "/generate 'abstract visualization of neural network connections, dark background with glowing blue nodes, futuristic style' --preview"
```

## Icon Generation

```bash
gemini --yolo "/icon 'minimalist app logo for productivity tool' --sizes='64,128,256,512' --type='app-icon' --corners='rounded'"
```

## Diagram Generation

```bash
gemini --yolo "/diagram 'user authentication flow with OAuth' --type='flowchart' --style='modern'"
```

## Output Location

All generated images are saved to `./nanobanana-output/` in the current directory.

## Presenting Results

After generation completes:
1. List contents of `./nanobanana-output/` to find generated files
2. Present the most recent image(s) to the user
3. Offer to regenerate with variations if needed

## Refinements and Iterations

When the user asks for changes:
- **"Try again" / "Give me options"**: Regenerate with `--count=3`
- **"Make it more [adjective]"**: Adjust prompt and regenerate
- **"Edit this one"**: Use `gemini --yolo "/edit nanobanana-output/filename.png 'adjustment'"`
- **"Different style"**: Add `--styles="requested_style"` to the command

## Prompt Tips

1. **Be specific**: Include style, mood, colors, composition details
2. **Add "no text"**: If you don't want text rendered in the image
3. **Reference styles**: "editorial photography", "flat illustration", "3D render", "watercolor"
4. **Specify aspect ratio context**: "wide banner", "square thumbnail", "vertical story"

## Troubleshooting

| Problem | Solution |
|---------|----------|
| `GEMINI_API_KEY` not set | `export GEMINI_API_KEY="your-key"` |
| Extension not found | Run install command from setup section |
| Quota exceeded | Wait for reset or switch to flash model |
| Image generation failed | Check prompt for policy violations, simplify request |
| Output directory missing | Will be created automatically on first run |