Module face_alignment 

Face alignment via affine warp using 5 facial landmarks.

Given 5 landmarks (left_eye, right_eye, nose, left_mouth, right_mouth) detected by YuNet or other face detectors, computes a similarity transform that maps them to canonical ArcFace reference positions, then warps the source image to produce an aligned face crop.

Supports arbitrary output sizes:

• 112x112 for ArcFace recognition (default)
• 128x128 for inswapper face swapping
• any custom size (reference points are scaled proportionally)

The algorithm used is a simplified Umeyama estimator for 2D similarity transforms (rotation + uniform scale + translation).

Reference: S. Umeyama, “Least-Squares Estimation of Transformation Parameters Between Two Point Patterns”, IEEE TPAMI, 1991.

Constants

ALIGNED_FACE_SIZE

Default aligned face size (112x112, same as ARCFACE_FACE_SIZE).

ARCFACE_FACE_SIZE

Output size for ArcFace recognition (112x112).

INSWAPPER_FACE_SIZE

Output size for inswapper face swapping (128x128).

Functions

align_face

Aligns a face by warping the source image using 5 detected landmarks.

align_face_sized

Aligns a face by warping the source image to an arbitrary output size.