A Novel Technique for Prealignment in Multimodality Medical Image Registration
Figure 7
Simulated orientation test by gradient magnitude weighted orientation histogram matching of T1 MRI (Figure 2(a)) and rotated T2 MRI (Figure 2(c)) images. (a) and (b) are the original images and the red circle which is largest centered at the images shows the area of overlap for orientation histogram accumulation. (c) and (d) are magnitude weighted orientation histograms for (a) and (b), respectively. (e) and (f) are the normalized histograms of (c) and (d), respectively. (g) shows the values of cost functions T of histogram (e) and (f) with shift for . The similarity metric is tested by L1 and L2 norm, respectively. The minimum value of the cost function T corresponds to along the horizontal coordinate. The obtained orientation difference is 11°, which is very close to its desired value.
