Generate/edit images with Nano Banana Pro (Gemini 3 Pro Image). Use for image create/modify requests incl. edits. Supports text-to-image + image-to-image; 1K...
---
name: nano-banana-pro
description: Generate/edit images with Nano Banana Pro (Gemini 3 Pro Image). Use for image create/modify requests incl. edits. Supports text-to-image + image-to-image; 1K/2K/4K; use --input-image.
---
# Nano Banana Pro Image Generation & Editing
Generate new images or edit existing ones using Google's Nano Banana Pro API (Gemini 3 Pro Image).
## Usage
Run the script using absolute path (do NOT cd to skill directory first):
**Generate new image:**
```bash
uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "your image description" --filename "output-name.png" [--resolution 1K|2K|4K] [--api-key KEY]
```
**Edit existing image:**
```bash
uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "editing instructions" --filename "output-name.png" --input-image "path/to/input.png" [--resolution 1K|2K|4K] [--api-key KEY]
```
**Important:** Always run from the user's current working directory so images are saved where the user is working, not in the skill directory.
## Default Workflow (draft → iterate → final)
Goal: fast iteration without burning time on 4K until the prompt is correct.
- Draft (1K): quick feedback loop
- `uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "<draft prompt>" --filename "yyyy-mm-dd-hh-mm-ss-draft.png" --resolution 1K`
- Iterate: adjust prompt in small diffs; keep filename new per run
- If editing: keep the same `--input-image` for every iteration until you’re happy.
- Final (4K): only when prompt is locked
- `uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "<final prompt>" --filename "yyyy-mm-dd-hh-mm-ss-final.png" --resolution 4K`
## Resolution Options
The Gemini 3 Pro Image API supports three resolutions (uppercase K required):
- **1K** (default) - ~1024px resolution
- **2K** - ~2048px resolution
- **4K** - ~4096px resolution
Map user requests to API parameters:
- No mention of resolution → `1K`
- "low resolution", "1080", "1080p", "1K" → `1K`
- "2K", "2048", "normal", "medium resolution" → `2K`
- "high resolution", "high-res", "hi-res", "4K", "ultra" → `4K`
## API Key
The script checks for API key in this order:
1. `--api-key` argument (use if user provided key in chat)
2. `GEMINI_API_KEY` environment variable
If neither is available, the script exits with an error message.
## Preflight + Common Failures (fast fixes)
- Preflight:
- `command -v uv` (must exist)
- `test -n \"$GEMINI_API_KEY\"` (or pass `--api-key`)
- If editing: `test -f \"path/to/input.png\"`
- Common failures:
- `Error: No API key provided.` → set `GEMINI_API_KEY` or pass `--api-key`
- `Error loading input image:` → wrong path / unreadable file; verify `--input-image` points to a real image
- “quota/permission/403” style API errors → wrong key, no access, or quota exceeded; try a different key/account
## Filename Generation
Generate filenames with the pattern: `yyyy-mm-dd-hh-mm-ss-name.png`
**Format:** `{timestamp}-{descriptive-name}.png`
- Timestamp: Current date/time in format `yyyy-mm-dd-hh-mm-ss` (24-hour format)
- Name: Descriptive lowercase text with hyphens
- Keep the descriptive part concise (1-5 words typically)
- Use context from user's prompt or conversation
- If unclear, use random identifier (e.g., `x9k2`, `a7b3`)
Examples:
- Prompt "A serene Japanese garden" → `2025-11-23-14-23-05-japanese-garden.png`
- Prompt "sunset over mountains" → `2025-11-23-15-30-12-sunset-mountains.png`
- Prompt "create an image of a robot" → `2025-11-23-16-45-33-robot.png`
- Unclear context → `2025-11-23-17-12-48-x9k2.png`
## Image Editing
When the user wants to modify an existing image:
1. Check if they provide an image path or reference an image in the current directory
2. Use `--input-image` parameter with the path to the image
3. The prompt should contain editing instructions (e.g., "make the sky more dramatic", "remove the person", "change to cartoon style")
4. Common editing tasks: add/remove elements, change style, adjust colors, blur background, etc.
## 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 watercolor painting")
Preserve user's creative intent in both cases.
## Prompt Templates (high hit-rate)
Use templates when the user is vague or when edits must be precise.
- Generation template:
- “Create an image of: <subject>. Style: <style>. Composition: <camera/shot>. Lighting: <lighting>. Background: <background>. Color palette: <palette>. Avoid: <list>.”
- Editing template (preserve everything else):
- “Change ONLY: <single change>. Keep identical: subject, composition/crop, pose, lighting, color palette, background, text, and overall style. Do not add new objects. If text exists, keep it unchanged.”
## 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
## Examples
**Generate new image:**
```bash
uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "A serene Japanese garden with cherry blossoms" --filename "2025-11-23-14-23-05-japanese-garden.png" --resolution 4K
```
**Edit existing image:**
```bash
uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py --prompt "make the sky more dramatic with storm clouds" --filename "2025-11-23-14-25-30-dramatic-sky.png" --input-image "original-photo.jpg" --resolution 2K
```
don't have the plugin yet? install it then click "run inline in claude" again.
extracted and formalized intent, inputs (including env var setup and external API connection), decision points (resolution mapping, generation vs editing, api key source, input validation, error cases, network fallback), and output contract with exact file format and dimensions; preserved original procedure and examples faithfully.
Generate new images or edit existing ones using Google's Nano Banana Pro API (Gemini 3 Pro Image). Use this skill for any image creation or modification request, whether text-to-image generation or image-to-image editing. Supports three resolutions (1K, 2K, 4K) and works best with iterative prompting (draft at 1K, final at 4K).
Generate or edit images using Google's Nano Banana Pro (Gemini 3 Pro Image) API. Use when a user requests image creation from text, image editing/modification, or image generation with specific style/composition requirements. Best for fast iteration: start at 1K resolution for prompt validation, bump to 4K only when the prompt is locked. Supports both text-to-image and image-to-image workflows.
Required:
GEMINI_API_KEY env var or --api-key flag)yyyy-mm-dd-hh-mm-ss-descriptive-name.png)Conditional:
--input-image)Environment / Setup:
uv command-line tool must be installed and in PATHGEMINI_API_KEY env var set, or API key passed as --api-key argumentExternal Connection:
Preflight checks:
uv is installed: run command -v uvGEMINI_API_KEY env var or plan to pass --api-key flagtest -f "path/to/input.png"Parse user intent:
Map resolution request to API parameter:
1KGenerate output filename:
yyyy-mm-dd-hh-mm-ss using current date/time (24-hour)x9k2){timestamp}-{descriptive-name}.pngBuild command:
uv run ~/.codex/skills/nano-banana-pro/scripts/generate_image.py--prompt "user prompt or editing instructions"--filename "generated-filename.png"--input-image "path/to/input.png"--resolution 1K|2K|4K (explicit, always include)--api-key KEYExecute from user's current working directory:
Capture and report output:
For resolution mapping:
1K (default, fast feedback)2K4K (only when prompt is finalized)For generation vs. editing:
--input-image parameter; treat as image-to-image--input-image)For API key source:
--api-key KEY flagGEMINI_API_KEY env varFor input image validation (editing only):
--input-image path does not exist or is unreadable: script fails with "Error loading input image"For quota/auth failures:
For empty/null results:
For network timeouts:
--filename path)yyyy-mm-dd-hh-mm-ss-descriptive-name.png (exact timestamp format required, lowercase name, hyphens)/home/user/project/2025-11-23-14-23-05-japanese-garden.png)Image saved to: /path/to/filename.png