Simon Willison’s Weblog

25th January 2009 - Link Blog

OCR and Neural Nets in JavaScript. John dissects the brilliant Greasemonkey script that solves simple captchas using the canvas element and HTML5’s getImageData API.

Posted 25th January 2009 at 12 am

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Thoughts on OpenAI acquiring Astral and uv/ruff/ty - 19th March 2026
GPT-5.4 mini and GPT-5.4 nano, which can describe 76,000 photos for $52 - 17th March 2026
My fireside chat about agentic engineering at the Pragmatic Summit - 14th March 2026

This is a link post by Simon Willison, posted on 25th January 2009.

canvas 38 captchas 8 getimagedata 1 greasemonkey 54 javascript 745 john-resig 33 ocr 25

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