Blind Watermarking of Color Medical Images Using Hadamard Transform and Fractional-Order Moments

This paper proposes a new blind, color image watermarking method using fast Walsh–Hadamard transformation (FWHT) and multi-channel fractional Legendre–Fourier moments (MFrLFMs). The input host color image is first split into 4 × 4 non-interfering blocks, and the MFrLFMs are computed for each block, where proper MFrLFMs coefficients are selected and FWHT is applied on the selected coefficients. The scrambled binary watermark has been inserted in the quantized selected MFrLFMs coefficients. The proposed method is a blind extraction, as the original host image is not required to extract the watermark. The proposed method is evaluated over many visual imperceptibility terms such as peak signal-to-noise ratio (PSNR), normalized correlation (NC), and bit error rate. The robustness of the proposed method is tested over several geometrical attacks such as scaling, rotation, cropping, and translation with different parameter values. The most widely recognized image processing attacks are also considered, e.g., compressing and adding noise attacks. A set of combination attacks are also tested to analyze the robustness of the proposed scheme versus several attacks. The proposed model’s experimental and numerical results for invisibility and robustness were superior to the results of similar watermarking methods.

Performance analysis of transformation and Bogdonov chaotic substitution based image cryptosystem

<span lang="EN-US">In this article, a combined Pseudo Hadamard transformation and modified Bogdonav chaotic generator based image encryption technique is proposed. Pixel position transformation is performed using Pseudo Hadamard transformation and pixel value variation is made using Bogdonav chaotic substitution. Bogdonav chaotic generator produces random sequences and it is observed that very less correlation between the adjacent elements in the sequence. The cipher image obtained from the transformation stage is subjected for substitution using Bogdonav chaotic sequence to break correlation between adjacent pixels. The cipher image is subjected for various security tests under noisy conditions and very high degree of similarity is observed after deciphering process between original and decrypted images.</span>

On the Sanctuary of a Combined Confusion and Diffusion based scheme for Image Encryption

Confusion and diffusion are the frequently used embryonics in multimedia (image) encryption systems. Multimedia data protection against cryptanalysis can be effectually fortified by these techniques. Due to inherent properties of images such as high inter-pixel redundancy and bulk data capacity, encryption is performed in two stages: Confusion and Diffusion. In this article, a combined Pseudo Hadamard transformation in the confusion stage and Gingerbreadman chaotic substitution in the diffusion stage are used in the encryption phase of the algorithm. The strong correlation between contiguous elements in the host image is effectually reduced using Pseudo Hadamard transformation and entropy in the cipher image is enhanced using Gingerbreadman chaotic substitution. Secrete key length used in the algorithm is 128 bits, these are the initial conditions for Gingerbreadman chaotic generator. The elements of S-box in the substitution stage are considered from this random sequence generator. Experimental exploration including information entropy, correlation analysis, sensitivity analysis, key space analysis and computational complexity have been performed on set of standard images. Results obtained are better compared to many existing systems.

Design and analysis of pseudo hadamard transformation and non-chaotic substitution based image encryption scheme

In this paper, Pseudo Hadamard Transformation (PHT) and non-chaotic substitution based image encryption scheme has been proposed. Images are characterized by intrinsic properties such as, strong redundancy and correlation between the adjacent pixels, hence more vulnerable to cyber-attacks. In the proposed technique, the redundancy and correlation have been effectively reduced by pixel position transformation using PHT and pixel value variation using non chaotic substitution, providing two stage security in encryption for images. Fifteen standard test images are considered for experimental analysis. Better average Number of Pixel Changing Rate (NPCR) and Unified Average pixel Changing Intensity (UACI) are obtained for a set of standard test images compared to more popular existing algorithms.

Design and Implementation of Transformation and Non-Chaotic Substitution Based Image Cryptosystem

In this article, a Modified Pseudo Hadamard Transformation (MPHT) and non-Chaotic substitution based image encryption scheme has been proposed. Due to intrinsic properties such as, strong redundancy and correlation between the adjacent pixels, images are more vulnerable to cyber-attacks. In the proposed technique, the redundancy and correlation have been effectively reduced by pixel position transformation using MPHT and pixel value variation using non chaotic substitution, providing two stage security in encryption for secrete images. An average 99.6089% of Number of Pixel Changing Rate (NPCR) and 33.4328% of Unified Average pixel Changing Intensity (UACI) are obtained for a set of standard test images compared to more popular existing techniques