(Top row) Images reconstructed by use of SGD with a constant step size of 2.5 × 105 and regularization parameter values of (a) 1 × 10−10, (b) 3 × 10−10, (c) 1 × 10−9, and (d) 3 × 10−9. (Bottom row) Images reconstructed by use of the weighted RDA method with regularization parameter values of (e) 1 × 10−10, (f) 3 × 10−10, (g) 1 × 10−9, and (h) 3 × 10−9. Images are shown after 100 iterations and in a grayscale window of [1.38, 1.60] mm/μs.