External Fractional-Order Gradient Vector Perona-Malik Diffusion for Sinogram Restoration of Low-Dosed X-Ray Computed Tomography

Figure 2

LDCT images in Figures 1(b) and 1(d) processed by FOPMD and EFOGV-PMD with different fractional-orders and iteration number is set to 15. The first column: 𝛼=0.5; the second column: 𝛼=0.8, the third column: 𝛼=1.2. The first row: Figure 1(b) processed by FOPMD; the second row: Figure 1(b) processed by EFOGV-PMD; the third row: Figure 1(d) processed by FOPMD; the fourth row: Figure 1(d) processed by EFOGV-PMD.

(a) LDCT image in Figure 1(b) processed by FOPMD in [9] with 𝜎=30, 𝛼=0.5, and 𝜆=1/7 and iteration number is 15 

(b) LDCT image in Figure 1(b) processed by FOPMD in [9] with 𝜎=30, 𝛼=0.8, and 𝜆=1/7 and iteration number is 15

(c) LDCT image in Figure 1(b) processed by FOPMD in [9] with 𝜎=30, 𝛼=1.2, and 𝜆=1/7 and iteration number is 15

(d) LDCT image in Figure 1(b) processed by EFOGV-PMD with 𝜎=30, 𝛼=0.5, and 𝜆=1/7 and iteration number is 15

(e) LDCT image in Figure 1(b) processed by EFOGV-PMD with 𝜎=30, 𝛼=0.8, and 𝜆=1/7 and iteration number is 15

(f) LDCT image in Figure 1(b) processed by EFOGV-PMD with 𝜎=30, 𝛼=1.2, and 𝜆=1/7 and iteration number is 15

(g) LDCT image in Figure 1(d) processed by FOPMD in [9] with 𝜎=30, 𝛼=0.5, and 𝜆=1/7 and iteration number is 15

(h) LDCT image in Figure 1(d) processed by FOPMD in [9] with 𝜎=30, 𝛼=0.8, and 𝜆=1/7 and iteration number is 15

(i) LDCT image in Figure 1(d) processed by FOPMD in [9] with 𝜎=30, 𝛼=1.2, and 𝜆=1/7 and iteration number is 15

(j) LDCT image in Figure 1(d) processed by EFOGV-PMD with 𝜎=30, 𝛼=0.5, and 𝜆=1/7 and iteration number is 15

(k) LDCT image in Figure 1(d) processed by EFOGV-PMD with 𝜎=30, 𝛼=0.8, and 𝜆=1/7 and iteration number is 15

(l) LDCT image in Figure 1(d) processed by EFOGV-PMD with 𝜎=30, 𝛼=1.2, and 𝜆=1/7 and iteration number is 15