banner-creator

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

examples/images/github-banner-01.png

examples/images/github-banner-02.png

examples/images/github-banner-03.png

Audit 0.4.1 · source sha a5004a4238e6 · 27 Oct 2026Report an issue or request a re-scan

• Publisherresciencelab GitHub organizationOwner of the repository this skill is read from
• Source folderresciencelab/opc-skills/skills/banner-creatorThe exact folder we audited
• LicenceApache-2.0As the repository states it
• Commit pinned for this verdicta5004a4238e6A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Create banners using AI image generation. Discuss format/style, generate variations, iterate with user feedback, crop to target ratio. Use when user wants to create a banner, header, hero image, cover image, GitHub…

---
name: banner-creator
description: Create banners using AI image generation. Discuss format/style, generate variations, iterate with user feedback, crop to target ratio. Use when user wants to create a banner, header, hero image, cover image, GitHub banner, Twitter header, or readme banner.
---

# 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](https://aistudio.google.com/apikey)

**Required Skills:**
- `nanobanana` - AI image generation (Gemini 3 Pro Image)



## File Output Location

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

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

**Example:**
```
.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:**
1. **Purpose** - Where will the banner be used?
   - GitHub README
   - Twitter/X header
   - LinkedIn banner
   - Website hero
   - YouTube channel art

2. **Target ratio/size** - See [references/formats.md](./references/formats.md):
   - `2:1` (1280x640) - GitHub README
   - `3:1` (1500x500) - Twitter header
   - `16:9` (1920x1080) - Website hero

3. **Style preference**:
   - Match existing logo/brand?
   - Pixel art / 8-bit retro
   - Minimalist / flat design
   - Gradient / modern
   - Illustrated / artistic

4. **Content elements**:
   - Brand name / project name?
   - Tagline / slogan?
   - Logo character to include?

5. **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:
1. Generate 10-20 more variations of favorite styles
2. Use naming: `banner-{original}-v{n}.png` (e.g., `banner-03-v1.png`)
3. Update HTML preview
4. 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:

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

**With Character:**
```
Wide banner featuring {character description}, {style} style, {scene}, text "{brand name}" on {position}, {colors}
```

**Abstract/Gradient:**
```
Abstract {style} banner, {colors} gradient, geometric patterns, modern tech feel, text "{brand}" centered
```

**Scene-based:**
```
{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](./references/formats.md) - Common banner sizes by platform
- [examples/opc-banner-creation.md](./examples/opc-banner-creation.md) - Full example conversation

Excerpt, first 5,357 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

1. 2026-10-27
   ✓SAFE B 89 / 100

   first audit · source a5004a4238e6

Questions about banner-creator

• github.com/resciencelab/opc-skills/tree/main/skills/banner-creat — the audited source at commit a5004a4238e6 and every finding aboveObserved · 27 Oct 2026

Spotted something wrong? Report a correction · Methodology