Canon Dual Pixel CMOS AF

Dual Pixel CMOS AF enables every imaging pixel on a supported CMOS sensor to perform both phase-detection autofocus and image capture. Each pixel is split into two independent photodiodes (side-by-side or top/bottom), allowing the camera to compare light arriving at the two halves for phase detection, and then combine the full signal for image output.^[2]

Unlike earlier systems that used separate AF sensors or sparse on-sensor AF pixels, Dual Pixel allows autofocus across a wide central area – about 80% of the frame in early implementations (e.g. EOS 70D) — with later mirrorless models realizing nearly 100% frame coverage.^[3]