Fig. 9: The variation of central moments during the isotropic blurring process of the noisy images.
From: Fast autofocusing based on single-pixel moment detection

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