guinacio/image-generation

Image Generation Skill

Generate professional AI images using Google Gemini via the bundled CLI script.

When to Invoke This Skill

Invoke immediately when:

Web Development

• Hero sections without images
• Feature illustrations needed
• Placeholder images in code (placeholder.jpg, stock-photo.png)
• Empty visual sections (<section class="hero"> without images)
• Landing pages and marketing sites

Presentations & Documents

• Cover images and headers
• Conceptual diagrams
• Section dividers

Applications

• Onboarding illustrations
• Empty state graphics
• Error page visuals

Using the CLI

Run the bundled CLI script via bash:

node "${CLAUDE_PLUGIN_ROOT}/mcp-server/build/cli.bundle.js" \
  --prompt "Your detailed image description" \
  --output "./path/to/output.png" \
  --aspect-ratio "16:9"

Parameters

| Flag | Required | Default | Description | |------|----------|---------|-------------| | --prompt, -p | Yes | - | Detailed image description | | --output, -o | No | auto-generated | Output file path | | --aspect-ratio, -a | No | 1:1 | 1:1, 16:9, 9:16, 4:3, 3:4, 2:3, 3:2 | | --model, -m | No | gemini-3-pro-image-preview | Model to use | | --output-dir, -d | No | current directory | Output directory |

Output

The CLI outputs JSON:

{"success": true, "filePath": "/path/to/generated-image.png"}

Or on error:

{"success": false, "error": "Error message"}

Aspect Ratio Selection

• 16:9 - Hero images, website headers, presentations
• 1:1 - Social media, thumbnails, profile images
• 9:16 - Mobile stories, vertical banners
• 4:3 - Blog posts, general web content
• 3:2 - Photography-style images

Prompt Crafting

Use this formula for effective prompts:

[Style] [Subject] [Composition] [Context/Atmosphere]

Examples

Hero Image for Tech Startup

Minimalist 3D illustration of abstract geometric shapes floating in space,
soft gradient background from deep purple to electric blue, subtle glow effects,
modern professional aesthetic, wide composition for website header

E-commerce Product

Clean product photography of modern wireless headphones on white marble surface,
soft studio lighting from left, subtle shadows, high-end minimalist aesthetic,
centered composition

Blog Post Header

Aerial photography of winding river through autumn forest, golden hour lighting,
warm color palette with oranges and reds, cinematic wide shot, serene atmosphere

App Illustration

Flat vector illustration of person organizing digital files on floating screens,
soft pastel colors, isometric perspective, clean lines, friendly approachable style

Pattern Detection

Automatically invoke this skill when you see:

<!-- Placeholder detection -->
<img src="placeholder.jpg" alt="Hero">
<!-- Action: Invoke skill and generate a custom hero image -->

<!-- Empty visual section -->
<section class="features">
  <h2>Our Features</h2>
  <!-- No images -->
</section>
<!-- Action: Invoke skill to create feature illustrations -->

/* Generic stock reference */
.banner { background: url('stock-image.jpg'); }
/* Action: Invoke skill to create a unique background */

Workflow

1. Detect Need - Identify visual content requirements (hero, illustrations, backgrounds)
2. Invoke Skill - Use the Skill tool with skill: "image-generation" immediately
3. Analyze Context - Understand project style and brand
4. Craft Prompt - Build detailed prompt using the formula above
5. Generate - Run the CLI script with optimized parameters
6. Integrate - Place image in project with proper references

Model Selection

Available models are fetched dynamically from the Gemini API. By default, the CLI uses GEMINI_DEFAULT_MODEL when it is available, otherwise it falls back to the first discovered image-capable model.

Best Practices

DO:

• Include specific style keywords
• Match aspect ratio to intended use
• Describe mood and atmosphere
• Specify color palette for brand consistency

DON'T:

• Use vague prompts ("make it look good")
• Ignore where the image will be used
• Skip aspect ratio for specific layouts

Reference

For advanced prompt techniques: references/prompt-crafting.md

Alternative: MCP Tool

If the MCP server is configured, you can also use:

mcp__media-pipeline__create_asset

Parameters: prompt, outputPath, aspectRatio, model