Fig. 7: The variation of central moments during the process of anisotropic blurring of the images.
From: Fast autofocusing based on single-pixel moment detection

Relationship between central moments (M1, M2 and M1 + M2) and variance (σx and σy) of the elliptic 2D Gaussian point spread function for img1 (a), img2 (b), img3 (c), and img4 (d).