Selective Medical Image Encryption and Compression Based on DCT, 3D_Att_ResU-Net and 4D Hyperchaotic Map Schemes

Medical image encryption has currently drawn particular attention because of the sensitive nature of medical data, the lack of efficient image encryption employing innovative encryption methods.To enhance the encryption of medical images, a number of encryption approaches were suggested and created.This research proposes a hyperchaotic map as well as a deep learning (DL) based selective medical image encryption technique.Initially, the 3D_Att_ResU-Net segments more sensitive region of interest (ROI) which is the brain tumours.The process continues with a hyperchaotic map for encrypting the ROI of plain medical image.On the other hand, the region of non interest (RONI) is compressed based on discrete cosine transform (DCT).The encrypting of ROI as well as compression of the background could provide the best possible balance between encryption performance and security.The samples for the simulation included a variety of common medical image types as well as a few normal images.The outcomes have been analysed using standard image cryptanalysis techniques.The findings demonstrated that cipher-images had uniformly distributed histogram, high information entropy, low correlation between neighbouring pixels, and good visual quality.The method has a large key space as well as low time complexity, yet it is sensitive to the plain image and the initial key.Interestingly, it has been found that the values of NPCR and UACI are higher than 99.75% and 36.53%, respectively besides large key space registered as an order of 2 339 .The entropy of the Region of Interest (ROI) is roughly estimated to be 8, which is significantly represent a better security for the current system.The estimated encryption time required for the ROI of size 8.09 KB is 0.3s and to compress the RONI of size 73.81 is 1.02s while the total time required to encrypt whole image of size 81.9 is 2.4737s making it suitable for real time applications.The results depict that the current presented encryption scheme gives high security with less computational time and complexity.