# Generate Image > Generate images using the Gemini API. Creates illustrations, thumbnails, icons, diagrams, photos, and visual assets from text prompts. Use when this capability is needed. - Skill: `tomevault-io/generate-image` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/generate-image` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/generate-image/raw - Safety review: pending (external: skill-scanner PASS, skillspector CAUTION) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/generate-image --- # Nano Banana Image Generation Generate professional images via the Gemini API's native image generation models. ## 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. ## Prerequisites Verify API key is set: ```bash [ -n "$GEMINI_API_KEY" ] && echo "API key configured" || echo "Missing GEMINI_API_KEY" ``` If missing, ask the user to set it: ```bash export GEMINI_API_KEY="your-key-from-aistudio.google.com/apikey" ``` ## Models | Model | Best For | Max Resolution | Speed | |-------|----------|---------------|-------| | `gemini-2.5-flash-image` | Fast generation, high-volume, general use | 1024px | Fast | | `gemini-3-pro-image-preview` | Professional assets, complex prompts, text rendering, 4K | Up to 4K | Slower (thinking model) | **Default model: `gemini-2.5-flash-image`** for most requests. **Use `gemini-3-pro-image-preview`** when user needs: 4K resolution, accurate text in images, complex multi-element compositions, professional asset production, or Google Search grounding. ## Image Generation (Text-to-Image) ```bash curl -s "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash-image:generateContent?key=$GEMINI_API_KEY" \ -H 'Content-Type: application/json' \ -d '{ "contents": [{"parts": [{"text": "YOUR PROMPT HERE"}]}], "generationConfig": { "responseModalities": ["TEXT", "IMAGE"] } }' | python3 -c " import json, sys, base64 data = json.load(sys.stdin) if 'error' in data: print('API Error:', data['error'].get('message', str(data['error']))) sys.exit(1) candidates = data.get('candidates', []) if not candidates: print('No candidates returned') sys.exit(1) parts = candidates[0].get('content', {}).get('parts', []) for part in parts: if 'inlineData' in part: img_data = base64.b64decode(part['inlineData']['data']) mime = part['inlineData'].get('mimeType', 'image/png') ext = 'png' if 'png' in mime else 'jpg' outpath = 'OUTPUT_PATH_HERE.' + ext with open(outpath, 'wb') as f: f.write(img_data) print(f'Image saved to: {outpath} ({len(img_data)} bytes)') elif 'text' in part and not part.get('thought'): print('Model notes:', part['text'][:300]) " ``` ### With Aspect Ratio Add `imageConfig` to control aspect ratio: ```bash curl -s "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash-image:generateContent?key=$GEMINI_API_KEY" \ -H 'Content-Type: application/json' \ -d '{ "contents": [{"parts": [{"text": "YOUR PROMPT HERE"}]}], "generationConfig": { "responseModalities": ["TEXT", "IMAGE"], "imageConfig": { "aspectRatio": "16:9" } } }' | python3 -c "SAME_DECODER_SCRIPT" ``` ## Image Editing (Image + Text to Image) To edit an existing image, base64-encode it and include it as an `inlineData` part: ```bash python3 -c " import base64, json, subprocess, sys with open('INPUT_IMAGE_PATH', 'rb') as f: b64 = base64.b64encode(f.read()).decode() payload = { 'contents': [{'parts': [ {'inlineData': {'mimeType': 'image/png', 'data': b64}}, {'text': 'YOUR EDIT INSTRUCTION HERE'} ]}], 'generationConfig': { 'responseModalities': ['TEXT', 'IMAGE'] } } result = subprocess.run( ['curl', '-s', 'https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash-image:generateContent?key=' + '$GEMINI_API_KEY_VALUE', '-H', 'Content-Type: application/json', '-d', json.dumps(payload)], capture_output=True, text=True ) data = json.loads(result.stdout) if 'error' in data: print('API Error:', data['error'].get('message', str(data['error']))) sys.exit(1) for part in data.get('candidates', [{}])[0].get('content', {}).get('parts', []): if 'inlineData' in part: img_data = base64.b64decode(part['inlineData']['data']) with open('OUTPUT_PATH', 'wb') as f: f.write(img_data) print(f'Image saved ({len(img_data)} bytes)') elif 'text' in part and not part.get('thought'): print('Model notes:', part['text'][:300]) " ``` ## Aspect Ratios | Ratio | Use Case | |-------|----------| | 1:1 | Square social (IG, LinkedIn) | | 16:9 | Blog featured, YouTube thumbnail | | 9:16 | Vertical story | | 3:2 | Landscape photo | | 21:9 | Twitter/X header | ## Prompt Tips 1. **Describe the scene narratively** — a descriptive paragraph beats a tag list 2. **Add "no text"** if you don't want text rendered in the image 3. **Be hyper-specific** — instead of "fantasy armor" say "ornate elven plate armor, etched with silver leaf patterns" 4. **Use photography terms** for photorealistic results — camera angles, lens types, lighting 5. **Reference artistic styles** — "editorial photography", "flat illustration", "3D render", "watercolor" ## Presenting Results After generation: 1. Read the generated image file to show it to the user 2. Offer to regenerate with variations or different models if needed --- > Source: [ash-ai-org/ash-ai](https://github.com/ash-ai-org/ash-ai) — distributed by [TomeVault](https://tomevault.io).