Rasterbator

About Rasterbator

Rasterbator is a free, browser-based tool that transforms any digital image into a large-scale wall poster using halftone dot patterns. No sign-up, no uploads, no watermarks — everything runs locally in your browser.

What is Rasterbation?

Rasterbation is the process of converting a digital image into an array of halftone dots spread across multiple printed pages. When assembled and viewed from a distance, the dots blend together to recreate the original image — the same optical illusion used in newspaper printing since the 1800s. The technique allows anyone with a standard home printer to create wall-sized artwork.

How Rasterbator Works

  1. 1

    Upload any JPG or PNG image (up to 40 MB). Your image stays on your device — nothing is sent to a server.

  2. 2

    Configure your poster: choose paper size, number of pages, halftone style, dot shape, colors, and grid density.

  3. 3

    Rasterbator analyzes each region of your image and replaces it with a proportionally sized dot. Dark areas get large dots, light areas get small dots.

  4. 4

    Download a multi-page PDF or ZIP of individual JPG tiles. Print at 100% scale, trim along crop marks, and assemble your poster.

Features

  • ✓11 rendering effects: classic halftone, color halftone, black & white, high contrast, horizontal lines, vertical lines, cross halftone, heart, triangle, ASCII art, and plain tile
  • ✓6 dot shapes: circle, square, diamond, heart, triangle, cross
  • ✓9 paper sizes: A5, A4, A3, A2, A1, US Letter, US Legal, Tabloid, and custom dimensions
  • ✓Full color control: custom dot and background colors with quick presets
  • ✓Real-time preview with zoom controls
  • ✓Multi-page PDF output with crop marks and page labels
  • ✓ZIP export with individual JPG tiles
  • ✓7 languages: English, Chinese, Spanish, French, Turkish, German, Portuguese
  • ✓Dark mode support
  • ✓100% client-side processing — complete privacy

History

The original Rasterbator was created in 2004 by Finnish developer Matias Ärje as a university project. It quickly became one of the most popular free poster-making tools on the internet, with millions of posters generated. The original site ran as a server-side application where users uploaded images for processing. This modern version reimagines the classic Rasterbator for today's web — built with Next.js and Web Workers, it runs entirely in your browser with no server uploads, offering better performance, more effects, and complete privacy.

Tips for Best Results

  • •Use high-resolution images (12 megapixels or higher) for the sharpest results.
  • •For classic halftone, a grid size of 10mm works well for large posters; use 5-7mm for finer detail.
  • •Always print at 100% scale — never use 'fit to page' or your tiles won't align.
  • •Standard 80gsm copy paper works fine; use 100-120gsm for posters you want to keep long-term.
  • •Laser printers produce sharper dots than inkjet printers.
  • •Lay out all pages on a flat surface before taping. Trim margins along crop marks for a seamless result.
  • •View your finished poster from 1.5-2x the poster width away for the best visual effect.

Technology

Rasterbator is built with Next.js 15, TypeScript, and Tailwind CSS. Image processing uses Web Workers and OffscreenCanvas for non-blocking rendering. PDF generation is handled by jsPDF, and ZIP export by JSZip. The entire application is statically exported and hosted on Cloudflare Pages for fast global delivery.