thumbnail

name	thumbnail
description	Generate video cover frames and thumbnails for YouTube, TikTok, Reels, and social media. Use when asked for a video thumbnail, cover frame, YouTube thumbnail, or to extract a still from a video.

Thumbnail — Video Cover Frames & Thumbnails

Generate optimized video thumbnails / cover frames for YouTube, TikTok, and social media.

Two Approaches

A. Extract Best Frame from Video (ffmpeg)

# Extract I-frame (keyframe) — usually sharpest
ffmpeg -i video.mp4 -vf "select=eq(pict_type\,I)" -frames:v 1 -q:v 2 thumb.jpg

# Extract frame at specific timestamp
ffmpeg -ss 00:00:05 -i video.mp4 -frames:v 1 -q:v 2 thumb.jpg

# Extract multiple candidate frames (one every 5 seconds)
ffmpeg -i video.mp4 -vf "fps=1/5" -q:v 2 thumb_%03d.jpg

After extracting candidates, review them with the image tool and pick the best one (sharpest, best expression, good composition).

B. Generate Custom Thumbnail (AI Image Generation)

Use the image_generate tool directly or any image generation skill to generate a designed thumbnail from scratch.

Prompt guidance:

• Include a face/subject with clear expression
• Specify text overlay in the prompt (keep to 3-5 words)
• Request high contrast, bright colors
• Match the platform aspect ratio (see specs below)

Example prompt structure: "YouTube thumbnail, 16:9, [subject description], [expression/action], bold text '[YOUR TEXT]', bright [color] background, high contrast, photorealistic"

Platform Specs

Platform	Size	Aspect	Notes
YouTube	1280x720	16:9	Custom upload. Most important for CTR.
TikTok	1080x1920	9:16	Select from video frames only (no custom upload).
Instagram Reels	1080x1920	9:16	Can set cover frame from video.
YouTube Shorts	1080x1920	9:16	Auto-selected from video.

Best Practices

• Faces with expression increase CTR 30%+
• High contrast colors (avoid muted tones)
• Large text (3-5 words max, readable at small size)
• Don't repeat the title verbatim
• Rule of thirds for subject placement
• Bright background or colored border to stand out in feed
• For YouTube: test with mobile preview size (the thumbnail is tiny on phone)

Adding Text to an Extracted Frame (ffmpeg)

# Centered text near bottom with black outline
ffmpeg -i thumb.jpg -vf "drawtext=text='3 MISTAKES':fontsize=80:fontcolor=white:borderw=4:bordercolor=black:x=(w-text_w)/2:y=h-text_h-50" thumb_text.jpg

# Top-left text
ffmpeg -i thumb.jpg -vf "drawtext=text='WATCH THIS':fontsize=72:fontcolor=yellow:borderw=3:bordercolor=black:x=40:y=40" thumb_text.jpg

For more complex text layouts (drop shadows, multiple text blocks, custom fonts), use AI image generation (see approach B above) to generate the thumbnail instead.

Workflow

1. Determine approach: Does the user have a video to extract from (→ A) or need a generated thumbnail (→ B)?
2. Confirm platform: YouTube 16:9 vs. vertical 9:16. Default to YouTube 1280x720 if unspecified.
3. Extract or generate: Run the appropriate approach.
4. Add text if needed: Use ffmpeg drawtext for simple overlays, or regenerate with AI image generation if complex.
5. Review: Screenshot/display the result for user approval.