Nano Banana Image Generation & Editing
Generate new images or edit existing ones using Google's Gemini image API.
Default model: Nano Banana 2 (gemini-3.1-flash-image-preview) — cheaper, faster, more features. Legacy model: Nano Banana Pro (gemini-3-pro-image-preview) — available via --model nano-banana-pro, deprecated 9 March 2026.
Usage
Run the script using absolute path (do NOT cd to skill directory first):
Generate new image:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "your image description" --filename "output.png" [--resolution 0.5K|1K|2K|4K] [--aspect-ratio 16:9] [--thinking high] [--api-key KEY]Edit existing image:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "editing instructions" --filename "output.png" --input-image "path/to/input.png" [--resolution 0.5K|1K|2K|4K] [--api-key KEY]Multi-reference generation (up to 14 images):
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "combine these styles" --filename "output.png" --input-image "ref1.png" --input-image "ref2.png"Important: Always run from the user's current working directory so images are saved where the user is working, not in the skill directory.
Model Selection
| Flag value | Model ID | Notes |
|---|---|---|
nano-banana-2 (default) | gemini-3.1-flash-image-preview | Cheaper, faster, 0.5K support, aspect ratio, thinking, 14 ref images |
nano-banana-pro | gemini-3-pro-image-preview | Deprecated 9 March 2026 |
Resolution Options
Uppercase K required:
- 0.5K — ~512px (cheapest, Nano Banana 2 only)
- 1K (default) — ~1024px
- 2K — ~2048px
- 4K — ~4096px
Map user requests:
- "thumbnail", "small", "cheap", "low resolution" →
0.5K - No mention / "1080", "1080p", "1K" →
1K - "2K", "2048", "medium resolution" →
2K - "high resolution", "high-res", "hi-res", "4K", "ultra" →
4K
When editing, resolution auto-detects from input image size if not specified.
Aspect Ratio
14 supported ratios (Nano Banana 2 only). Omit to let the API decide.
Map user requests:
- "landscape", "wide" →
16:9 - "portrait", "phone", "story", "reel" →
9:16 - "square" →
1:1 - "cinematic", "ultrawide" →
21:9 - "photo portrait" →
3:4or2:3
Thinking
Controls reasoning effort for complex prompts (Nano Banana 2 only). Omit for fastest/cheapest.
--thinking minimal— slightly better quality, low latency impact--thinking high— best for complex composition, text rendering, detailed scenes
Note: thinking tokens are billed regardless of level.
Reference Images
Up to 14 input images via repeated --input-image flags. Use cases:
- Style transfer — provide style reference + subject
- Character consistency — provide character reference images
- Object reference — provide object images to include
- Image editing — provide single image + editing instructions in prompt
Resolution auto-detects from the first input image when --resolution not specified.
API Key
Checked in order:
--api-keyargumentGEMINI_API_KEYenvironment variable
Filename Generation
Pattern: yyyy-mm-dd-hh-mm-ss-name.png
- Timestamp: current date/time, 24-hour format
- Name: descriptive lowercase with hyphens (1-5 words)
- Unclear context: use random identifier (e.g.,
x9k2)
Examples:
- "A serene Japanese garden" →
2026-03-01-14-23-05-japanese-garden.png - Unclear →
2026-03-01-17-12-48-x9k2.png
Image Editing
- Check if user provides an image path or references an image in the current directory
- Use
--input-imagewith the path - Pass editing instructions in
--prompt - Common tasks: add/remove elements, change style, adjust colours, blur background
Prompt Handling
For generation: Pass user's image description as-is to --prompt. Only rework if clearly insufficient.
For editing: Pass editing instructions in --prompt (e.g., "add a rainbow in the sky", "make it look like a watercolour painting")
Preserve user's creative intent in both cases.
Output
- Saves PNG to current directory (or specified path if filename includes directory)
- Script outputs the full path to the generated image
- Do not read the image back — just inform the user of the saved path
Pricing (Paid Tier Only)
No free tier for image generation.
Nano Banana 2 (gemini-3.1-flash-image-preview) — default
| Resolution | Standard | Batch |
|---|---|---|
| 0.5K (512px) | $0.045 | $0.022 |
| 1K | $0.067 | $0.034 |
| 2K | $0.101 | $0.050 |
| 4K | $0.151 | $0.076 |
Google Search grounding: 5,000 prompts/month free, then $14/1,000 queries.
Nano Banana Pro (gemini-3-pro-image-preview) — deprecated 9 Mar 2026
| Component | Standard | Batch |
|---|---|---|
| Input (per image) | $0.0011 | $0.0006 |
| Output 1K/2K | $0.134 | $0.067 |
| Output 4K | $0.24 | $0.12 |
Examples
Generate with aspect ratio:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "Cinematic landscape at golden hour" --filename "2026-03-01-10-00-00-landscape.png" --resolution 2K --aspect-ratio 21:9Generate with thinking for complex prompt:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "A detailed infographic about climate change with text labels" --filename "2026-03-01-10-05-00-infographic.png" --thinking high --resolution 4KMulti-reference style transfer:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "A portrait in this artistic style" --filename "2026-03-01-10-10-00-styled-portrait.png" --input-image "style-ref.png" --input-image "subject.png"Budget thumbnail:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "Simple icon of a house" --filename "2026-03-01-10-15-00-house-icon.png" --resolution 0.5KEdit existing image:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "make the sky more dramatic with storm clouds" --filename "2026-03-01-14-25-30-dramatic-sky.png" --input-image "original-photo.jpg" --resolution 2KUse legacy model:
uv run ~/.claude/skills/nano-banana/scripts/generate_image.py --prompt "A serene Japanese garden" --filename "2026-03-01-14-23-05-japanese-garden.png" --model nano-banana-pro --resolution 4K