Figure 3
Method to find the effective displacement of two projections at 0° and 180°. (a) For each displacement the mean squared difference (black curve) and its gradient (gray curve) is computed. (b) Zoom in to the offset position at which the function exposes a minimum which is characterized by a notch-like shape, indicated by the biggest jump in the gradient (dashed line). (c) Detector systems with increasing signal-to-noise ratios (6, 20, 44 dB) have been simulated by adding Gaussian noise. The stability of the algorithm is demonstrated by using only five rows (dash-dotted lines) of each image to compute . |