Fig. 7From: Improving SVD-based image watermarking via block-by-block optimization on singular valuesWatermarked images for k = 4. a Watermarked image of Lena (q = 55). b Watermarked image of Jet (q = 44). c Watermarked image of Peppers (q = 51). d Watermarked image of Cameraman (q = 50)Back to article page