“… Singular value decomposition (SVD), Genetic algorithm (GA) | Host image of size 256 × 256: Lena; Watermark image of size: 32 × 32 (grey-level) | Correlation coefficient (CC), PSNR | Rotation, Average filter, Scaling, Gaussian noise, Gamma correction, Histogram, Median filter | In the proposed method, GA is utilized to obtain multiple scaling factors (SF) for achieving the highest possible robustness without degrading image quality. | [ 7 ] | This paper provides a comparison between PSO and JAYA as well as between LWT and DWT | LWT, DWT, DCT, SVD, PSO, JAYA | Host grayscale image: 512 × 512; Watermark grayscale: 256 × 256 | PSNR, SSIM, Normalized correlation coefficient (NCC), Mean square error (MSE) | JPEG compression, Gaussian noise, Median filter, Salt and Pepper, Low pass filter, Sharpening, Gamma correction, Scaling, Translation | The proposed work has been tested under different attacks and found robust and imperceptible. |
[ 8 ] | To improve the watermarked image’s integrity and perceived quality and to enhance the security of watermarking | DWT, SVD, Quantization, | Shore, Lena, Baboon, Pepper, Dark cloud: 200 × 200 | PSNR, Bit error rate (BER) | JPEG compression, Gaussian noise, Median filter, Cropping | The enhanced perceptual quality of the watermarked images and the proposed scheme preserve high PSNR. |
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