--- 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 "" --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 "" --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: . Style: