Your left-right boundary search is actually a CUDA-friendly single scan

Fri, 26 Jun 2026 20:00:00 +0800

At least, most of the time it is. As long as it fits the 1-2-1 pattern..

Many segments can be boiled down to what I call a 1-2-1 pattern. For an array of input elements (I’ll just call them pixels, it’s shorter for me to type), a naive segment detection is to loop forwards until you hit an activation pixel. This can internally be any condition you’d like; that is, any if (...) is possible here as long as you operate only on the pixel you’re currently at. For simplicity, I’ll assume this is the 2 pixel:

Scans on icyveins7's blog

Your left-right boundary search is actually a CUDA-friendly single scan