From the comparison, our algorithm presents better performance in NPCR and UACI
The comparison of key space is shown in Table 5 and the NPCR and UACI
between Figures 37(a) and 37(b)-37(f) are calculated in Table 6.
The second criterion, UACI
, is used to measure the average intensity of differences between the two images.
The number of pixels change rate (NPCR) and the unified average changing intensity (UACI
) are two important metrics for differential attack analysis.
They have obtained the closest entropy of decrypted image (DI) to that of original image listed in Table 1, the least MSE, the largest PSNR, the maximum cross correlation coefficient between original and decrypted images, and the least value for UACI
. The elapsed time has been minimum in case of the first proposed DWT based technique.
The ideal expectations of NPCR and UACI
can be calculated by the following simplified formulas:
Of our scheme, the NPCR is more than 99% and the UACI
is more than 33%, which proves that the proposed scheme is sensitive.
= [1/[[M.sub.1] x [M.sub.2]]][summation over (i,j)][[absolute value of ([c.sub.1](i,j) - [c.sub.2](i,j))]/255] x 100%, (8)
Jefe(a) Unidad de Adquisiciones y Contrataciones Institucional (UACI
To test the influence of one-pixel change on the plainimage, encrypted by the proposed ECBFSC, two common measures may be used: Number of Pixels Change Rate (NPCR) and Unified Average Changing Intensity (UACI