# Image Watermarking Scheme Using LSB and Image Gradient
###### Abstract
The substitution box is the counter-clockwise component used in cryptosystems, providing cryptosystems with the confusion property defined by [PERSON] in his famous paper [8]. The basic features of cryptography such as confusion and diffusion correspond with the features of chaos [9]. Chaotic systems have many exciting features, such as mixing property, ergodicity, and sensitivity to initial conditions; these characteristics of chaos make them ideal to design an S-Box with chaos [10]. The S-Box design using chaos is dynamic in nature, while the S-Box used in AES and DES is static in nature. The security strength of block ciphers depends upon the substitution box. Some recent research related to digital image watermarking is summarized here. [PERSON] et al. [11] proposed an image watermarking based on fractional Fourier transform. This scheme could withstand image handling tasks like JPEG compression, but it had high computational cost due to its complexity. [PERSON] et al. [12] suggested a blind watermarking approach using discrete cosine and lifting wavelet transform. In this approach, the watermark image showed high imperceptibility. The major concern of this approach is making the watermark imperceptible regardless of the robustness against attacks. [PERSON] et al. [13] suggested a spatialdomain watermarking approach relying on the distribution feature of the direct current coefficient. This technique incorporated the computational efficiency and robustness features of the spatial domain and frequency domain. The extracted watermark robustness can be compared with other image watermarking techniques. [PERSON] [14] offered a method combining image filtering with image watermarking and improved the privacy of watermark images. [PERSON] et al. [15] combined a weber descriptor, chaotic map, and DCT transform for blind medical image watermarking, where the weber descriptor was used for embedding and extraction processes. The planned method showed good results, but it had some limitations in implementation. [PERSON] et al. [16] proposed a method based on curvelet domain, which showed good progress in watermark embedding and watermark extraction time, but the structure similarity of the watermarked image was not good. Another technique based on all phase discrete cosine biorthogonal transform (APDCBT), DWT, and SVD was proposed by [PERSON] et al. [17]. This technique used DC coefficients for embedding and extracting the watermark, because of its better perceptual capacity than AC coefficients. The PSNR and robustness against attacks were good, but the technique was computationally expensive. In [18], a digital image watermarking technique based on DCT, DWT, and SVD was recommended. This technique was robust against geometric attacks. The disadvantage of this technique was its effect on the host image. The comparative literature comparison is given in Table 1.  
The remainder of the paper is arranged as follows: Section 3 proposes the methodology for watermark implanting and watermark extraction; Section 4 presents and discusses the experimental evaluation; Moreover, Section 5 provides the conclusion.