[Retracted] Robust and Secure Zero-Watermarking Algorithm for Medical Images Based on Harris-SURF-DCT and Chaotic Map

Figure 11

Some attacked medical and extracted watermarks under conventional attacks: (a) Gaussian Noise 30%. (b) JPEG compression 5%. (c) Median filter 7 × 7, 20 times.

(a)

(b)

(c)