A Robust Fractal Color Image Watermarking Algorithm

Table 2

Extracted watermarks (EW) and NCs after attacked by median filter (3×3, 5×5, 7×7), mean filter (3×3, 5×5, 7×7), sharpening, and blurring of the three images: Lena, Barbara, and Peppers.

	Median filter			Mean filter			Sharpening	Blurring
	3×3	5×5	7×7	3×3	5×5	7×7
Lena
EW
NC	0.9937	0.9421	0.8593	0.9764	0.8832	0.7648	0.9872	0.9847
Barbara
EW
NC	0.9966	0.9502	0.8641	0.9796	0.8837	0.7561	0.9957	0.9900
Peppers
EW
NC	0.9780	0.9288	0.8456	0.9437	0.8392	0.7111	0.9675	0.9629