Building a Dynamic Image Generation Pipeline with Gemini AI and Sharp in Node.js

Every developer eventually faces the same problem: you need to generate images programmatically. Maybe it is social media posts that need to go out daily, marketing assets for dozens of product variants, or dynamic Open Graph images for a blog. Hiring a designer for every permutation is not scalable. Using Canva templates feels brittle. What you actually want is a pipeline — AI generates the base image, your code handles the rest. In this article, we will build exactly that. We will use Google's Gemini API to generate images from structured prompts, then Sharp to post-process them: circular logo overlays, text via SVG, format conversion, and multi-platform sizing. Everything in TypeScript, everything you can drop into a CI job or cron. Architecture Overview The pipeline has three stages: [Structured Prompt] → [Gemini API] → [Raw PNG Buffer] ↓ [Sharp Pipeline] ↓ ┌───────────────┼───────────────┐ ↓ ↓ ↓ [1080x1080] [1080x1920] [1000x1500] Instagram Stories Pinterest Feed / Reels Gemini ge