generate-youtube-thumbnail

Files (1)

• SKILL.md

SKILL.md (first lines)

# Generate YouTube Thumbnail

A reusable workflow for creating YouTube thumbnails via KIE.ai's Nano Banana 2 image model with proper character likeness and proven CTR formulas.

## When to use this skill

Trigger on phrases like:
- "make me a YouTube thumbnail"
- "create a thumbnail for this video"
- "I need thumbnail variations / A/B tests"
- "remake this thumbnail with my face"
- "generate 10 thumbnail concepts"
- "thumbnail with [me / my product / my brand]"

## Read order

1. **This file** — workflow, decision tree, batch generation
2. **[shared/skills/generate-youtube-thumbnail/prompting/guide.md](../../shared/skills/generate-youtube-thumbnail/prompting/guide.md)** — likeness alignment, expressions cheat sheet, prompt structure (shared across all generative-AI APIs in this portfolio)
3. **[shared/skills/generate-youtube-thumbnail/prompting/formulas.md](../../shared/skills/generate-youtube-thumbnail/prompting/formulas.md)** — 5 proven thumbnail formulas with templates (shared)
4. **[scripts/generate-batch.sh](scripts/generate-batch.sh)** — KIE-specific batch script (URL-based references, jobs endpoint)

## Prerequisites

- `.env` with `KIE_API_KEY`
- Reference images **hosted at PUBLIC URLs** before the batch runs. KIE has no presigned
  upload flow — reference images in `input.image_input` must be reachable URLs (your own
  CDN/bucket, an image host, GitHub raw, etc.). The batch script does NOT upload for you.
- Suggested reference categories (the script reads URLs from arrays you fill in):
  - `face/` — 5+ photos of the subject (headshot + 3/4 angles + close-ups + expressions)
  - `logos/` — brand logos
  - `products/` — clean product shots
  - `examples/` — real ad screenshots, comparison material
  - `style/` — example thumbnails the user wants to match aesthetically

If references are missing or the user pastes images in chat instead of providing URLs,
**stop and ask the user for either (a) public URLs for each reference, or (b) file paths
they can upload to a host themselves.** Chat paste is not a URL.

## Workflow

### 1. Gather requirements (in order)

Ask the user for any missing context, but only what you actually need:

1. **Concept** — what's the video about? Single concept, A/B variations, or specific recreation of an existing thumbnail style?
2. **Subject** — who is in the thumbnail (the user themselves, an AI character, no person)?
3. **Brand assets** — which logos / products / brand colors should appear?
4. **Text** — what should the title text say? Will text be baked in, or added in post (Canva/Photoshop)?
5. **Comparison material** — for "real vs AI" thumbnails, what real ad and what AI-generated ad?

### 2. Verify reference URLs are reachable

```bash
for url in "${REF_URLS[@]}"; do
  curl -I -s -o /dev/null -w "%{http_code} %{url_effective}\n" "$url"
done
```

Each URL must return `200`. If any return 4xx/5xx, ask the user to re-host or share a new URL. **Do not proceed with text-only descriptions for brand-specific items** (logos, branded products, branded apparel) — you'll get generic AI approximations that don't match the brand. Generic descriptions are OK for backgrounds, expressions, and clothing.

### 3. Estimate cost and confirm

Always present cost as an **estimate** before firing:

> "Estimated cost: N variations × {per-image rate from MASTER_CONTEXT.md} = X credits. Confirm exact pricing in [kie.ai/logs](https://kie.ai/logs) after the run."

### 4. Pick a formula

See **[shared/skills/generate-youtube-thumbnail/prompting/formulas.md](../../shared/skills/generate-youtube-thumbnail/prompting/formulas.md)** for the 5 proven formulas. Match the user's intent:

| User says... | Use formula |
|---|---|
| "Just me with my brand" / "branding thumbnail" | **Peace-sign / branding** |
| "Real vs AI" / "compare" / "before/after" | **Real vs AI comparison** |
| "Show the process" / "with the terminal" | **Terminal flow** |
| "Surprised face" / "shocked reaction" | **Reaction shock** |
| "Replace" / "alternative" / "swap out" | **Before/after split** |

### 5. Compose prompts

Follow the template in **[shared/skills/generate-youtube-thumbnail/prompting/guide.md](../../shared/skills/generate-youtube-thumbnail/prompting/guide.md)**:

```
YouTube thumbnail, 16:9 landscape.
[SUBJECT — likeness block + clothing + framing + "no hands" if applicable]
Expression: [specific expression from expressions cheat sheet]
[LEFT visual element + reference]
[RIGHT visual element + reference]
Across the top in massive bold yellow block letters with thick black outline reads [TITLE].
Background: [color + glow]
Style: [aesthetic notes]
Avoid: distorted face, extra fingers, hands visible, blurry logos, generic face
```

**Always include the CRITICAL CHARACTER LIKENESS block** when the subject is a real person. See `shared/skills/generate-youtube-thumbnail/prompting/guide.md`.

### 6. Generate (use the batch script)

Copy `scripts/generate-batch.sh` to a new versioned script (`scripts/generate-thumbnails-vN.sh`) and modify:

1. Update `COMMON_REF_URLS` array with your public reference URLs (one per reference image)
2. Replace the `PROMPTS` array entries with your composed prompts
3. Run with `bash scripts/generate-thumbnails-vN.sh > output/run.log 2>&1 &`
4. Monitor with `tail -F output/run.log | grep -E "DONE|FAILED|Task"`

The script handles:
- Optional local Lanczos upsample (if user supplies local files they plan to host)
- Parallel firing of `POST /api/v1/jobs/createTask` with `model: "nano-banana-2"`
- Retry on failure with backoff
- Polling `GET /api/v1/jobs/recordInfo?taskId=...` until `state: success` or `fail`
- Parsing `data.resultJson` for result URLs and downloading
- Session folder organization under `output/thumbnails-<timestamp>/`

### 7. Review and present

After all generations complete, read each thumbnail with the Read tool and present:

- Brief verdict per thumbnail (likeness, readability, emotional impact)
- Top 3 picks ranked by CTR potential

From harperaa/hermes-plugin-short-form, MIT.

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