INFOCOMP - Departamento de Ciência da Computação - Ufla

Dinesh Kumar and Vijay Chahar Digital Image Watermarking: A Review of SVD, DCT and DWT Based Approaches 32
Table 5: Correlation coefficients for Salt and pepper noise attacks Table 8: Correlation coefficients for Gaussian noise attacks with different
noise variances using Barbara as cover and bird as watermark
with different noise densities using Barbara as cover and logo as watermark
Den. Liu Gha Emir Haq Mis P rop
0.001 0.999 0.999 0.999 0.999 0.999 0.999
0.003 0.998 0.999 0.999 0.998 0.998 0.999
0.005 0.997 0.999 0.998 0.997 0.998 0.999
0.007 0.996 0.997 0.997 0.996 0.997 0.998
0.009 0.992 0.996 0.995 0.995 0.996 0.997
0.01 0.990 0.994 0.995 0.993 0.995 0.996
0.03 0.953 0.961 0.966 0.966 0.978 0.979
0.05 0.912 0.921 0.926 0.919 0.944 0.955
0.07 0.862 0.895 0.883 0.858 0.905 0.924
0.09 0.824 0.8554 0.8274 0.815 0.8764 0.898
V ar. Liu Gha Emir Haq Mis P rop
0.001 0.962 0.984 0.992 0.932 0.991 0.989
0.005 0.931 0.961 0.974 0.827 0.977 0.944
0.01 0.882 0.923 0.935 0.742 0.951 0.887
0.05 0.637 0.713 0.631 0.535 0.748 0.685
0.1 0.527 0.607 0.511 0.498 0.615 0.641
0.2 0.450 0.528 0.479 0.472 0.509 0.587
0.3 0.416 0.500 0.466 0.463 0.448 0.579
0.4 0.395 0.478 0.463 0.452 0.433 0.568
0.5 0.382 0.468 0.455 0.450 0.425 0.568
0.6 0.373 0.464 0.455 0.434 0.428 0.560
Table 6: Correlation coefficients for Salt and pepper noise attacks
with different noise densities using Barbara as cover and bird as watermark
Den. Liu Gha Emir Haq Mis P rop
0.001 0.999 0.999 0.998 0.998 0.998 0.999
0.003 0.998 0.997 0.998 0.998 0.997 0.998
0.005 0.995 0.997 0.998 0.998 0.995 0.998
0.007 0.991 0.995 0.995 0.995 0.993 0.997
0.009 0.988 0.991 0.994 0.994 0.987 0.995
0.01 0.985 0.989 0.992 0.993 0.986 0.994
0.03 0.939 0.943 0.959 0.967 0.934 0.966
0.05 0.883 0.892 0.910 0.917 0.873 0.955
0.07 0.834 0.848 0.847 0.866 0.829 0.924
0.09 0.796 0.818 0.768 0.819 0.781 0.898
methods have an edge over the proposed one.
Table 7: Correlation coefficients for Gaussian noise attacks with different
noise variances using Barbara as cover and logo as watermark
The result shows that proposed method gives better correlation
under different wavelets.
Figure 5 shows the effect of scaling factor on the wa-
Table 9: Correlation coefficients for different wavelet under sharpening
attack
W avelet Emir Mis P rop
Haar 0.824 0.772 0.874
Daubechies(db2) 0.787 0.208 0.836
Symlet(sym2) 0.787 0.208 0.868
Biorthogonal(bior2.2) 0.823 0.265 0.871
Coifman(coif2) 0.775 0.395 0.869
termarked image for proposed method.Peak Signal to
Noise Ratio (PSNR) for different scaling factors on watermarked
image is tabulated in Tables 10 and 11 for
one cover images and two watermark images.
V ar. Liu Gha Emir Haq Mis P rop
0.001 0.998 0.998 0.999 0.998 0.999 0.998
0.005 0.981 0.9841 0.989 0.987 0.992 0.990
0.01 0.951 0.960 0.968 0.963 0.976 0.977
0.05 0.747 0.795 0.759 0.736 0.844 0.813
0.1 0.616 0.684 0.573 0.579 0.727 0.758
0.2 0.510 0.593 0.476 0.431 0.633 0.644
0.3 0.464 0.557 0.438 0.415 0.569 0.597
0.4 0.443 0.532 0.425 0.410 0.549 0.593
0.5 0.422 0.512 0.422 0.408 0.534 0.589
0.6 0.419 0.507 0.418 0.402 0.519 0.585
Lastly,we perform the experiments to show the effect
of scaling factor and wavelet on proposed method.
Table 9 gives correlation coefficients for different
wavelets applying on proposed, Emric Ganic and Majumder
methods under image sharping attack using
barabara as cover image and bird as a watermark image.
Figure 5: Effect of scaling factor on watermarked image using Lena
as cover image and bird as watermark image
The results reveal that the increase in the value of
scaling factor results in decrease in PSNR. It means that
distortion in watermarked image increases when the
scaling factor increases. The results also demonstrate
that Liu and Ghazy methods give best quality image.
INFOCOMP, v. 10, no. 3, p. 25-35, September of 2011.