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

Table 6

Attacked images along with their corresponding retrieved logos using Elaine image and NUS 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↓	18.69	21.99	42.74	9.64	18.23	28.02	19.56	17.68	29.79
UROI	13.86, 90	12.79, 88	23.58, 99	∞, 100	16.97, 96	16.20, 94	13.49, 90	13.84, 84	19.02, 97
TBLK	17.33, 88	15.61, 84	26.51, 99	41.95, 99	19.82, 95	19.53, 91	16.04, 88	16.26, 85	23.80, 97
DCTMSB	14.48, 86	14.57, 86	27.32, 99	16.55, 81	18.37, 94	17.00, 91	15.64, 92	14.36, 81	24.03, 98
𝑡-DWT (𝑡=4)	17.84, 92	17.25, 93	33.09, 100	12.17, 70	21.20, 97	22.27, 97	15.75, 90	14.89, 86	33.09, 100
TROI [12]	16.40, 56	16.62, 55	17.50, 55	17.47, 55	14.72, 56	17.14, 56	15.99, 56	15.13, 56	17.26, 55
VQ [13]	21.12, 61	23.29, 55	25.35, 68	7.78, 48	22.76, 65	25.02, 65	20.27, 50	20.08, 65	25.35, 68

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 (%).