Paul Irish explains how pointerpointer.com works. It uses a hidden canvas of colored Voronoi regions to look up which photo matches the cursor position.
Why Hacker News points people here: HN links it as the author's own breakdown of Pointer Pointer's inner workings.
“Paul Irish did a breakdown of it quite a while ago”HN comment, 2020
“Paul Irish did a breakdown of it quite a while ago”
Breakdown of Pointer Pointer using Voronoi and manual tagging
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Here's a picture of all the different regions: link For those curious if how it works, Paul Irish did a breakdown of it quite a while ago: this video TL:DW - Vornoi Diagrams[1] and manual tagging, no machine learning needed. [1] link
Cites itpaulirishJun 2012
“I made a quick video explaining how the webapp works”
Explains how pointerpointer works
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I made a quick video explaining how the webapp works: this video Essentially, using the gridPositions.json to populate a Voronoi Grid (toggle display of the <canvas> in your browser). Then your cursor position is used against the grid to find which shape encloses it which maps back to the source JPEG which is then displayed.
Cites itpetercooperOct 2025
“Paul Irish explained the basics of how it works here”
Explains basics of how it works
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Paul Irish explained the basics of how it works here: this video I wonder if you could create something similar nowadays using generative AI but with the finger in a very specific location without pregenerating thousands of images.