Unmodified redistribution of face_detection_yunet_2026may.onnx from the OpenCV Zoo.

YuNet is a light-weight, fast and accurate face detection model (WIDER Face: 0.834 AP_easy / 0.824 AP_medium / 0.708 AP_hard) that detects faces of roughly 10×10 to 300×300 px. This is the dynamic-input-shape variant (the OpenCV Zoo default): compatible with OpenCV 5.x's ONNX Runtime engine and any ONNX runtime, allowing inference at any resolution without resizing. It is the same model with symbolic height/width — the weights are identical to the fixed-shape 2023mar variant.

input — float32 tensor [1, 3, height, width] (dynamic H/W): a BGR image, NCHW layout, no normalization. height and width must be multiples of 32 (the largest stride).

12 per-stride detection heads for strides s ∈ {8, 16, 32}, each shaped [1, A, C] with A = (height/s) · (width/s) anchors:

cv2.FaceDetectorYN (or an equivalent decode) turns these heads into per-face [x, y, w, h, 5 × (x, y), score].

MIT, following the upstream OpenCV Zoo.