# Gemini Image Gen > Use when asked to generate images (PNG/JPEG), SVG icons, SVG logos, or any visual asset - delegates to Gemini CLI for image generation and SVG code generation via gemini-3-pro model - Skill: `tomevault-io/gemini-image-gen` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/gemini-image-gen` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/gemini-image-gen/raw - Safety review: pending (external: skill-scanner PASS, skillspector WARNING) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/gemini-image-gen --- # Generating Images & SVGs with Gemini CLI ## Overview Gemini CLI can generate two types of visual output: - **SVG code**: Text-based vector graphics output directly from Gemini models (no API key needed) - **Raster images (PNG)**: Generated via the `nanobanana` extension (requires `GEMINI_API_KEY` env var) ## When to Use - User asks to "generate an image", "create an icon", "make a logo", "draw something" - User needs SVG code for icons, logos, illustrations, diagrams - User needs PNG/JPEG images (photos, artwork, UI assets) ## Quick Reference | Task | Model | Command Pattern | |------|-------|----------------| | SVG code | `gemini-3-pro-preview` | `gemini -m gemini-3-pro-preview -e none -p "..." --output-format text` | | SVG code (fallback) | `gemini-2.5-flash` | `gemini -m gemini-2.5-flash -e none -p "..." --output-format text` | | PNG image | `gemini-2.5-flash` | `gemini -m gemini-2.5-flash -p "Generate image... Save to [path]" -y` | ## Model Fallback Chain Always try the best model first, then fall back to cheaper/faster models on rate limit (429) errors. **SVG models** (in order): `gemini-3-pro-preview` → `gemini-2.5-flash` **Image models** (in order): `gemini-2.5-flash` → `gemini-2.5-flash` (retry after delay) **Fallback procedure:** 1. Run command with primary model, capture stderr via `2>&1` 2. Check output for `429`, `RESOURCE_EXHAUSTED`, or `capacity` → means rate limited 3. Retry with the next model in the chain 4. If all models fail, tell the user and suggest waiting ## SVG Generation — via Code Output (NOT Nanobanana) SVGs are generated as **text code output** by the model itself — NOT via nanobanana. Use `-e none` to disable extensions so Gemini outputs SVG code instead of trying to use image tools. ```bash # Try primary model first OUTPUT=$(gemini -m gemini-3-pro-preview -e none -p "Create an SVG icon of [description]. Output ONLY the raw SVG code, no markdown fences, no explanation." --output-format text 2>&1) # Check for rate limiting - fall back to cheaper model if echo "$OUTPUT" | grep -qi "429\|RESOURCE_EXHAUSTED\|capacity\|quota"; then OUTPUT=$(gemini -m gemini-2.5-flash -e none -p "Create an SVG icon of [description]. Output ONLY the raw SVG code, no markdown fences, no explanation." --output-format text 2>&1) fi # Save result echo "$OUTPUT" | sed '/^```/d' > output.svg ``` Or run them as separate commands - try the primary model first, and if you see rate limit errors in the output, immediately run the fallback. ### SVG Prompt Tips - Always end with: "Output ONLY the raw SVG code, no markdown fences, no explanation." - Specify dimensions: "200x200", "24x24 icon size" - Specify colors explicitly: "Use #FF6B35 orange and #1A1A2E dark blue" - Specify style: "flat design", "line art", "gradient", "minimalist" - For logos, include text requirements: "Include the text 'AppName' below the icon" ### Post-Processing SVG Output Gemini sometimes wraps output in markdown code fences. Strip them: ```bash # Generate and clean SVG output gemini -m gemini-3-pro-preview -e none -p "..." --output-format text | sed '/^```/d' > output.svg ``` After generating, read the file to verify valid SVG and show/return the code to the user. ## Image Generation (PNG) — via Nanobanana Extension PNG image generation uses **nanobanana**, a Gemini CLI extension that provides a `generate_image` tool. This is the ONLY way to generate real images — do NOT try to use Pillow, Python scripts, or `-e none`. ### How it works 1. Gemini CLI loads the `nanobanana` extension automatically on startup (you'll see `Loading extension: nanobanana` in output) 2. Gemini calls the `generate_image` tool provided by nanobanana 3. Nanobanana generates the image and saves it to the requested path ### Requirements - `GEMINI_API_KEY` environment variable must be set (configured in `~/.zshrc`) - Get a key from https://aistudio.google.com/apikey if not set - Do **NOT** pass `-e none` — that disables all extensions including nanobanana ### Save location Unless the user specifies a different path, always save generated images to `/tmp/`. Example: `/tmp/prishtina.png`, `/tmp/logo.png`. ### Command ```bash gemini -m gemini-2.5-flash -p "Generate a beautiful image of [description]. Save it to /tmp/[filename].png" -y --output-format text 2>&1 ``` ### Key rules - **NO `-e none`** — extensions must be enabled so nanobanana loads - **`-y` is required** — auto-approves the nanobanana tool call (YOLO mode) - **`--output-format text`** — keeps output clean - If you see `Loading extension: nanobanana` in stdout, it's working - If you see "No valid API key found", the `GEMINI_API_KEY` env var is missing - Best for: photorealistic images, artwork, cityscapes, illustrations, any visual content ## Prompt Handling **Default: pass the user's prompt as-is.** Always forward the user's words to Gemini without rewriting, embellishing, or adding details. Only append the save path instruction. Examples of prompts to pass verbatim: - "generate an image of Prishtina" → pass as-is - "generate an image of a cat sitting on a rooftop at sunset" → pass as-is - "make a logo with a blue mountain" → pass as-is **Only fill in details when the user explicitly delegates content to you** — e.g. "create some images to add to this page" or "generate a few images for this blog post". In those cases you choose subjects, composition, and style. ## Workflow for Claude When asked to generate visual assets: 1. **Determine type**: SVG (vector code) or PNG (raster image)? 2. **SVG path**: - Run with `gemini-3-pro-preview` first (best quality) - If output contains rate limit error → immediately retry with `gemini-2.5-flash` - Strip markdown fences, save to file, verify valid SVG 3. **PNG path** (uses nanobanana extension): - Run gemini **without** `-e none` and with `-y` so nanobanana loads and auto-approves - Confirm `Loading extension: nanobanana` appears in output - Specify save path in prompt, verify file exists after 4. **Always verify**: Read/check the output file exists and is valid before reporting success 5. **Show SVG code**: For SVGs, read the file and present the code to the user ## Common Issues | Problem | Solution | |---------|----------| | Model rate limited (429) | Use fallback model (gemini-2.5-flash for SVGs) or wait and retry | | SVG wrapped in markdown fences | Pipe through `sed '/^```/d'` | | gemini hangs in headless mode | Add timeout: `timeout 120 gemini -p "..."` | | SVG has no xmlns attribute | Add to prompt: "Include xmlns='http://www.w3.org/2000/svg'" | | PNG: "No valid API key found" | Set `GEMINI_API_KEY` env var (get from https://aistudio.google.com/apikey) | | PNG: nanobanana extension not loading | Don't use `-e none` for PNG generation — extensions must be enabled | --- > Source: [gentritbiba/agent-skills](https://github.com/gentritbiba/agent-skills) — distributed by [TomeVault](https://tomevault.io).