# Blind Watermarking of Color Medical Images Using Hadamard Transform and Fractional-Order Moments
###### Abstract  
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 \(\times\) 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. blind watermarking color medical images; geometric attacks; fractional-order moments; fast Walsh-Hadamard transform 202127845 [[https://doi.org/10.3390/s21237845](https://doi.org/10.3390/s21237845)]([https://doi.org/10.3390/s21237845](https://doi.org/10.3390/s21237845))  
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[PERSON], M.  
According to the extraction method, there are three common types of watermarking systems: blind, non-blind, and semi-blind watermarking [5]. In a blind watermarking [7] system, the host cover image is not required in the watermark extraction process; it just needs the watermarked image. In non-blind [8] watermarking, the host and the watermarked images are both required to extract the watermark image. In semi-blind watermarking [9], the watermarked image and security key are required to engage the extraction process fully. Concerning the desired security purpose of the watermarking models, there are three common characteristics: robustness [10], semi-fragile [11], and fragile [12] watermarking models. The robustness of the watermark system is that it resists a specific set of transformations such as geometric attacks. It is extensively used in copyright protection. The semi-fragile watermark system resists benign transformations only and can be detected after slight changes. It is used to detect and locate malignant transformations. The fragile watermark system cannot be detected after slight modification. It can be destroyed because it is highly sensitive to any slight modification; it is extensively used in tamper detection for proving integrity. In recent years, many authors have introduced many watermarking methods in using color images; therefore, color images play a significant role in real-life applications such as copyright provisions and image authenticity for medical applications and other similar fields. Many researchers have presented realistic watermarking approaches in the spatial and frequency working domains. [PERSON] et al. [13] introduced a blind watermarking method in the spatial domain by modifying the luminosity component, Y, of the transformed YCbCr model. The host color image is split into 8 \(\times\) 8 blocks, and a binary watermark has been embedded in a sorted correlation of values between corresponding blocks of sub-images. This scheme has been personalized, as it is low in robustness capabilities against various attacks. [PERSON] and [PERSON] [14] introduced a watermarking scheme in the spatial domain to solve this problem. A binary logo image is embedded directly in distributed features in the direct current (DC) coefficients. This method proved to be a robust watermarking system against several geometric and standard signal attacks.