A Medical Image Retrieval Algorithm Based on DFT Encryption Domain

摘要

The medical image needs to be encrypted before storing in cloud platform to protect against leaking the personal private information of medical image. And we expect the encrypted medical image can be retrieved automatically in cloud computing platform, but traditional medical image retrieval is based on the visual feature, which is difficult to identify with the naked eye after encryption. In this paper, we propose an algorithm with strong robustness— medical image retrieval algorithm based on DFT encryption domain. We encrypt the image in frequency domain and extract its feature vector to establish a feature database, and then automatically compute the NC (Normalized Cross Correlation Coefficient, NC) between the feature vector of the image to be retrieved and each one stored in the feature database. Finally, the corresponding encrypted image with the greatest value of NC is returned. The experimental results show that this algorithm has ideal ability to resist the conventional attack, such as interference of Gaussian noise, JPEG compressing and median filtering, and geometric attack, such as rotation, scaling, translation, cutting.