1.
The major originality of this paper lies that it utilizes the intra-block, inter-block, and inter-component dependencies of the encrypted color JPEG image to construct retrieval feature and reduces feature dimensionality by combining with multi-class SVM.
2.
For a color JPEG image, this scheme can ensure both format compliance and file size preservation before and after encryption.
3.
The scheme realizes privacy-preserving effective image retrieval in encrypted domain. Experiment results show that the overall retrieval performance of the proposed scheme is significantly improved.