Banner Creator Skill

Create professional banners through AI image generation with an iterative design process.

Prerequisites

Required API Keys (set in environment):

•GEMINI_API_KEY - Get from Google AI Studio

Required Skills:

•nanobanana - AI image generation (Gemini 3 Pro Image)

File Output Location

All generated files should be saved to the .skill-archive directory:

code

.skill-archive/banner-creator/<yyyy-mm-dd-summaryname>/

Example:

code

.skill-archive/banner-creator/2026-01-19-opc-banner/
  banner-01.png
  banner-02.png
  ...
  banner-03-cropped.png
  preview.html

Workflow

Step 1: Discovery & Requirements

Before generating, gather requirements from user:

Ask about:

•
Purpose - Where will the banner be used?
- •GitHub README
- •Twitter/X header
- •LinkedIn banner
- •Website hero
- •YouTube channel art
•
Target ratio/size - See references/formats.md:
- •2:1 (1280x640) - GitHub README
- •3:1 (1500x500) - Twitter header
- •16:9 (1920x1080) - Website hero
•
Style preference:
- •Match existing logo/brand?
- •Pixel art / 8-bit retro
- •Minimalist / flat design
- •Gradient / modern
- •Illustrated / artistic
•
Content elements:
- •Brand name / project name?
- •Tagline / slogan?
- •Logo character to include?
•
Color preferences:
- •Existing brand colors?
- •Let AI decide?

Wait for user confirmation before proceeding!

Step 2: Generate Banner Variations

Generate 20 banner variations using the nanobanana skill:

bash

# Generate single banner
python3 <nanobanana_skill_dir>/scripts/generate.py "{style} banner for {brand}, {description}, {text elements}" \
  --ratio 21:9 -o .skill-archive/banner-creator/<date-name>/banner-01.png

# Batch generate 20 banners
python3 <nanobanana_skill_dir>/scripts/batch_generate.py "{style} banner for {brand}, {description}, {text elements}" \
  -n 20 --ratio 21:9 -d .skill-archive/banner-creator/<date-name> -p banner

Guidelines:

•Generate at 21:9 ratio (widest available), crop later to target
•Use batch_generate.py for multiple variations (includes auto-delay)
•Use sequential naming: banner-01.png, banner-02.png, etc.

Image Editing (for incorporating existing logo):

bash

python3 <nanobanana_skill_dir>/scripts/generate.py "add {logo character} to the left side of the banner" \
  -i /path/to/existing-logo.png --ratio 21:9 -o banner-with-logo.png

Step 3: Create HTML Preview

Copy the preview template and open in browser:

bash

cp <skill_dir>/templates/preview.html .skill-archive/banner-creator/<yyyy-mm-dd-summaryname>/preview.html

Then open in default browser:

bash

open .skill-archive/banner-creator/<yyyy-mm-dd-summaryname>/preview.html

IMPORTANT: Update the HTML to include the correct number of banners generated.

Step 4: Iterate with User

Ask user which banners they prefer:

•"Which banners do you like? (e.g., #3, #7, #15)"
•"What do you like about them?"
•"Any changes you'd want?"

Based on feedback:

•Generate 10-20 more variations of favorite styles
•Use naming: banner-{original}-v{n}.png (e.g., banner-03-v1.png)
•Update HTML preview
•Repeat until user selects final banner

Step 5: Crop to Target Ratio

Once user approves a banner, crop to target size:

bash

python3 <skill_dir>/scripts/crop_banner.py {input.png} {output.png} --ratio 2:1 --width 1280

Common targets:

•GitHub README: --ratio 2:1 --width 1280 → 1280x640
•Twitter header: --ratio 3:1 --width 1500 → 1500x500
•Website hero: --ratio 16:9 --width 1920 → 1920x1080

Step 6: Deliver Final Assets

Present final deliverables:

code

## Final Banner Assets

| File | Description | Size |
|------|-------------|------|
| banner-03.png | Original (21:9) | 2016x864 |
| banner-03-cropped.png | GitHub README (2:1) | 1280x640 |

All files saved to: `.skill-archive/banner-creator/<yyyy-mm-dd-summaryname>/`
Copy final banner to user's desired location.

Quick Reference

Common Prompt Patterns

With Text:

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Wide banner for {brand}, {style} style, featuring "{text}" prominently displayed, {colors}, {scene/elements}

With Character:

code

Wide banner featuring {character description}, {style} style, {scene}, text "{brand name}" on {position}, {colors}

Abstract/Gradient:

code

Abstract {style} banner, {colors} gradient, geometric patterns, modern tech feel, text "{brand}" centered

Scene-based:

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{Style} illustration banner, {scene description}, {character} in {action}, "{brand}" text overlay, {colors}

Supported Aspect Ratios

Generate at widest ratio, then crop:

•21:9 - Ultra-wide (recommended for generation)
•16:9 - Wide
•3:2 - Standard wide

References

•references/formats.md - Common banner sizes by platform
•examples/opc-banner-creation.md - Full example conversation