Visual Security Assessment for Cipher-Images based on Neighborhood Similarity

In the recent decades, many practical algorithms have been put forward for images and videos encryption. However, there is no objective security assessment algorithm or calculation index has been proposed at present. According to the differences of pixel value and neighborhood distribution between cipher-images and original images, we present a visual security assessment algorithm based on neighborhood similarity. The experiment result shows that the scheme can provide an objective assessment which is match up to subjective assessment, and is also suitable for the security assessment of cipher-images produced by other selective encryption algorithms.