Robust Signature-Based Copyright Protection Scheme Using the Most Significant Gray-Scale Bits of the Image

Table 4

Attacked images along with their corresponding retrieved logos using Lena image and Monash logo by different approaches of the proposed MSB-based scheme and existing TROI-based [12] and VQ-based [13] schemes.

	Affine^2	BPM^3	Blurring^4	Crop.^5	Hist. Eq.	JPEG (5)	PCS^6	Rot.-crop 2°	unZign
Attacks^1→
Schemes^7↓	20.66	22.94	36.89	10.67	19.36	28.23	11.63	19.48	29.08
UROI	19.30, 96	14.36, 91	20.58, 99	∞,100	13.08, 86	16.89, 95	10.98, 72	16.12, 89	18.18, 97
TBLK	14.44, 88	12.97, 85	21.43, 96	13.16, 94	14.16, 89	15.06, 90	10.64, 71	10.26, 73	18.48, 94
DCTMSB	14.09, 94	11.19, 89	22.04, 99	13.75, 87	12.00, 86	12.81, 93	10.00, 72	11.84, 86	21.69, 98
𝑡-DWT (𝑡=4)	10.52, 88	15.18, 96	30.20, 100	6.69, 71	18.79, 98	16.75, 97	10.07, 78	11.61, 91	∞, 100
TROI [12]	14.73, 54	13.85, 56	14.97, 53	15.19, 53	16.94, 62	14.86, 48	13.20, 61	13.37, 53	14.68, 54
VQ [13]	14.79, 58	23.67, 73	23.12, 60	15.57, 83	17.10, 55	20.65, 53	20.72, 71	19.74, 64	23.38, 65

¹Attacked images with PSNR (dB).
²Resized to original after XY-shearing.
³PSNR of similar blocks (4×4) ≥25 dB.
⁴Gaussian filter.
⁵Cropping excluding ROI.
⁶Print-copy-scan.
⁷Retrieved logos with PSNR (dB) and LRR (%).