IMPLEMENTATION METHOD ON MEDICAL IMAGE COMPRESSION SYSTEM: A REVIEW <s> Figure 4 <s> This paper presents a practical implementation of a quasigroup based multilevel, indexed scrambling transformation for use in signal authentication, encryption, and broadcasting applications in secret-key cryptography. Results of experiments with text and speech scrambling are presented. It is shown that the quasigroup transformation is very effective in destroying the structure of the input signal and, therefore, it can be an excellent encryption technique. <s> BIB001 </s> IMPLEMENTATION METHOD ON MEDICAL IMAGE COMPRESSION SYSTEM: A REVIEW <s> Figure 4 <s> Three dimensional MRI images which are power tools for diagnosis of many diseases require large storage space. A number of lossless compression schemes exist for this purpose. In this paper we propose a new approach for the compression of these images which exploits the inherent symmetry that exists in the 3D MRI images. A block matching routine is employed to work on the symmetrical characteristics of these images. Another type of block matching is also applied to eliminate the inter-slice temporal correlations. The obtained results outperform the existing standard compression techniques. <s> BIB002 </s> IMPLEMENTATION METHOD ON MEDICAL IMAGE COMPRESSION SYSTEM: A REVIEW <s> Figure 4 <s> The arrival of CT and MRI imaging in the last two decades used for analysis of various diseases in medical field. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) sequences have become essential in healthcare systems and an integral segment of a patient's medical record. Such medical image data needed a huge amount of resources for storage and transmission. Compression of medical images for efficient use of storage space and transmission bit rate has become a necessity. A quasigroup successfully creates an astronomical number of keys which is used to confuse the hackers in determining the original data. However, quasi group encryption is not capable in diffusing the information of the plain text. Hence, in this study the DICOM images are encrypted using a chained Hadamard transforms and Number Theoretic Transforms to introduce diffusion along with the quasigroup transformation. A secure Fast Two Dimensional Discrete Fractional Fourier Transform (DFRFT) and a SPIHT Algorithm with Huffman Encoder is used for compress the image and it provides a secure compression of medical images as compared to the other transform. The experimental results evaluate the performance of the proposed encryption approach based on the PSNR and MSE it shows the proposed approach gives better results. <s> BIB003
Block diagram of proposed method of six stages of compression algorithm BIB002 An analysis of the discrete fractional Fourier transform (DFT) based medical image compression using a hybrid encoding technique was discussed in BIB003 . This system comprises of the following phases namely encryption; domain transformation; SPIHT algorithm with Huffman compression; decoding through SPIHT with Huffman encoder and inverse fast two-dimensional fractional Fourier transform; and finally, the quasi-group decryption with Hadamard and number theoretic transform. Hadamard transform is a generalized class of Fourier transforms, created either recursively, or through binary representation. The overall process diagram is shown in Figure 5 . A-part from that, the Hadamard and number theoretic transform act as hash functions which produce diverse hash values for different input values BIB001 . Whereas, there is a huge difference in the generated random sequence if there is a one-bit change in the input sequence. In brief, this proposed approach was observed as being capable of producing the best results for all the test images taken for consideration. The experimental results have shown higher PSNR values and lesser means squared error (MSE) values when compared with other existing techniques.