---
name: thumbnail-a-b-generator
description: Generate 5 thumbnail variants for a single video using a brand template and a topic prompt — ready for YouTube multi-variant testing.
title: Thumbnail A/B Generator
category: image-video
difficulty: beginner
author: admin
icon: 🖼️
input: mixed
output: image
phase: enhance
domain: design
tags: thumbnail-generation,youtube-optimization,ab-testing,image-composition,template-rendering,headline-variants,mobile-legibility,batch-image-creation,content-creator,video-marketing
best_for:
  - YouTube creators optimizing click-through rates
  - Content marketing teams running thumbnail A/B tests
  - Video agencies managing multi-channel distribution
  - Brand teams enforcing template consistency across creators
---

## Description

Input: a brand template (PNG with transparent spots for subject and text), a video topic, and an optional subject image. Output: 5 thumbnail variants with different headline angles, color accents, and subject placements — sized to 1280x720 and optimized for mobile-scale legibility.

## Why it works

YouTube rewards multi-variant thumbnail testing but most creators only make one. Generating five variants that each emphasize a different angle (question, number, emotion, curiosity gap, counter-intuitive claim) gives you something to actually test instead of 'this is my thumbnail.'

## How it works

1. Load the brand template — identify the subject slot and text slot coordinates. 2. Generate 5 headline angles from the topic via LLM, each under 5 words and tuned for mobile legibility. 3. For each variant, composite the subject image into the subject slot, render the headline at a legibility-checked font size, and apply an accent color from a rotating palette. 4. Run a quick legibility check — headlines must be readable at 200x120 preview size. 5. Emit the 5 variants as PNG + a caption with the angle rationale for each.