Fig. 15

Correlation distributions of (a1)–(a3) in the horizontal direction, diagonal direction, and horizontal direction, respectively, in the “red” channel of the color plaintext (“Peppers”) shown in Fig. 5(b1); (b1)–(b3) in the horizontal direction, diagonal direction, and horizontal direction, respectively, in the “green” channel of the color plaintext (“Peppers”) shown in Fig. 5(b2); (c1)–(c3) in the horizontal direction, diagonal direction, and horizontal direction, respectively, in the “blue” channel of the color plaintext (“Peppers”) shown in Fig. 5(b3); (d1)–(d3) in the horizontal direction, diagonal direction, and horizontal direction, respectively, in the ciphertext shown in Fig. 5j.