| name | youtube-thumbnails |
| description | This skill should be used when the user asks to "create YouTube thumbnails", "generate thumbnails", "make video thumbnails", or needs AI-generated thumbnail images via Google Gemini for YouTube videos. Covers prompt engineering, image generation, compression, and upload to YouTube Studio.
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| version | 0.1.0 |
YouTube Thumbnail Generation via Gemini
Overview
Generate custom YouTube thumbnails using Google Gemini's image generation (Pro mode). Each thumbnail is a 1280x720 image with bold text overlays, thematic visuals, and branding.
Step-by-Step Workflow
1. Gather Video Info
For each video that needs a thumbnail, collect:
- Title (already set on YouTube)
- Content type: "AI in Action" weekly jam or "Paper Club" reading
- Topic summary: What was presented/demoed (from frame extraction or title)
- Presenter name (optional, for subtitle text)
- Date in
D Mon YYYY format
2. Navigate to Gemini
- Go to
gemini.google.com
- Click Tools button (bottom toolbar)
- Enable Create images
- Click the model dropdown (shows "Fast" by default) and select Pro
- Confirm "Image" chip and "Pro" label appear in the chat input area
3. Craft the Thumbnail Prompt
Use this prompt template, customized per video:
Create a YouTube thumbnail (1280x720) for a video titled "[FULL TITLE]".
[1-2 sentences describing what the video is about — the demo, paper, or topic].
The visual should be [THEME DESCRIPTION]: [specific visual elements relevant to the topic].
Bold text overlay: "[MAIN TITLE]" prominently, with smaller text "[SUBTITLE]" below it.
Include a bottom bar with "[SERIES NAME] [D MON YYYY]" in bold.
Please include the Latent Space podcast logo in a corner — search the web for "Latent Space podcast logo" to find it.
Use [COLOR PALETTE] with a dark [THEME] background.
Prompt Customization by Content Type
AI in Action (demos/presentations):
- Bottom bar text:
AI IN ACTION [D MON YYYY]
- Visual theme: Match the demo topic (space, gaming, dev tools, etc.)
- Colors: Vibrant, exciting — neon blues, greens, purples, electric tones
Paper Club (paper readings):
- Bottom bar text:
PAPER CLUB [D MON YYYY]
- Visual theme: Academic but engaging — neural networks, brain visualizations, formulas
- Colors: Deep blue, orange, white — scholarly but modern
- Main text: Paper acronym or short name (e.g., "SDPO")
- Subtitle: Full paper name
Key Prompt Tips
- Always ask Gemini to search the web for relevant logos and reference images
- Specify 1280x720 dimensions explicitly
- Request bold, large text for the main title — readable at thumbnail size
- Include a colored bottom bar with the series name and date
- Keep the background dark so text pops
4. Generate and Save
- Submit the prompt and wait ~30-45 seconds for Pro mode generation
- Click the generated image to expand it
- Click Save to download to ~/Downloads
- Generated files will be named
Gemini_Generated_Image_[hash].jpeg
5. Compress to Under 2MB
YouTube requires thumbnails under 2MB. Gemini Pro images are typically 3-4MB.
convert "Gemini_Generated_Image_[hash].jpeg" -resize 1280x720 -quality 85 thumb_[label].jpg
Naming convention: thumb_[abbreviated_date].jpg (e.g., thumb_jan31.jpg, thumb_feb7.jpg)
6. Upload Thumbnails to YouTube Studio
For each video:
- Go to YouTube Studio → Content → click on the video
- Click the pencil/edit icon (Details tab) in the left sidebar
- Scroll to the Thumbnail section
- Click the Upload file button (may be hidden — use
find tool to locate ref)
- Select the correct
thumb_[date].jpg file
- Verify the thumbnail appears in the preview
- Click Save at the top right
File picker automation (macOS):
After clicking Upload file, use osascript to navigate the native file dialog:
tell application "System Events"
delay 1
keystroke "g" using {command down, shift down}
delay 1
keystroke "/path/to/thumb_[date].jpg"
delay 0.5
keystroke return
delay 1
keystroke return
end tell
7. Verify
Take a screenshot of each video's details page to confirm the custom thumbnail is set.
File Size Reference
- Gemini Pro raw output: ~3-4MB (too large)
- After
convert -resize 1280x720 -quality 85: ~200-250KB (well under 2MB limit)
- YouTube max thumbnail size: 2MB
- YouTube thumbnail dimensions: 1280x720 (16:9)
- Accepted formats: JPG, PNG, GIF
Example Prompts
Tech Demo Thumbnail
Create a YouTube thumbnail (1280x720) for a video titled "SpaceMolt - AI Agents in Multiplayer Space Games".
This is about a demo of SpaceMolt, a multiplayer space trading and mining game where AI agents autonomously play alongside human players.
The visual should be exciting and space-themed: spaceships, asteroids, neon glow, a dark cosmic background.
Bold text overlay: "SPACEMOLT" prominently, with smaller text "AI AGENTS IN SPACE GAMES" below it.
Include a bottom bar with "AI IN ACTION 7 FEB 2026" in bold.
Please include the Latent Space podcast logo in a corner — search the web for "Latent Space podcast logo".
Use vibrant sci-fi colors — electric blue, green, purple neon tones.
Academic Paper Thumbnail
Create a YouTube thumbnail (1280x720) for a video titled "RL via Self-Distillation (SDPO) Paper Reading".
This is an academic paper reading session about SDPO — Self-Distillation Preference Optimization.
The visual should be academic but engaging: neural network or brain visualization with mathematical formulas.
Bold text overlay: "SDPO" prominently, with smaller text "SELF-DISTILLATION PREFERENCE OPTIMIZATION" below it.
Include a bottom bar with "PAPER CLUB 12 FEB 2026" in bold.
Please include the Latent Space podcast logo in a corner — search the web for "Latent Space podcast logo".
Use deep blue, orange, and white color palette with a dark academic-themed background.
Troubleshooting
- "File is bigger than 2MB": Compress with ImageMagick
convert -resize 1280x720 -quality 85
- Gemini generation takes long: Pro mode takes 30-45 seconds. Wait and check with a screenshot.
- Upload button not visible: Use the
find tool to locate the hidden "Upload file" button by ref.
- File picker automation fails: Instruct user to manually select the file.
