I Built a YouTube Thumbnail Auto-Generator

Hey everyone, it’s Cody.

Making thumbnails for every YouTube video was getting tedious, so I built a tool that automatically generates thumbnails from your videos.

What It Does

Give it a video file or YouTube URL, and it automatically picks the best frames for thumbnails. Apply a style preset, and you’ve got a polished thumbnail ready to go.

There’s also a Web UI where you can drag and drop a video to preview every frame combined with every style at once.

Tech Stack

• Python 3.11+
• ffmpeg — Frame extraction from videos
• EasyOCR — Filters out frames with too much on-screen text
• Pydantic — Data models
• Click — CLI

How Frame Selection Works

Instead of grabbing random frames, the tool uses a multi-step process:

1. Scene detection — Detects scene changes in the video to determine sampling points
2. Scoring — Evaluates each frame for thumbnail suitability
3. Text detection filter — Uses EasyOCR to exclude frames with heavy text overlays (subtitles and captions make for bad thumbnails)

Results are cached, so regenerating with a different style is fast.

Style Presets

Four built-in styles are included:

Style	Look
type7_editorial	Film tones, warm but restrained, polished
type7_film	Faded warm colors, vignette, analog feel
type7_morning	Misty blue-gray, soft light, cool
type7_gallery	Ultra-low saturation, high contrast, art-house

Here are some actual thumbnails generated by the tool:

By the way, anyone catch what “type7” is a reference to? Porsche fans might get it. ;)

You can also create custom styles with TOML files. Image effects (darken, vignette, blur, etc.), text placement, fonts, and colors are all configurable.

Why I Built This

Most existing thumbnail tools are template-based — you manually drop in an image and add text. What I wanted was automatic selection of the best frame from the video itself. The ability to filter out frames with text overlays was especially important to me, since subtitle-heavy frames make terrible thumbnails.

If there’s enough interest, I’m considering making this available as a public service. If that sounds useful to you, feel free to hit the heart button.

Thanks for reading today.