For a blind source separation （BSS） based method for encrypting multiple images

the multiple decrypted im- ages by BSS may have changed order and reversed pixel values. In addition

decorrelation preprocessing must be per- formed prior to decryption of strongly correlated images. To solve the two problems

a novel method for image decryp- tion was proposed based on correlation calculation since the key images are known for legal users and are independent of the original images. Specifically

the correlation matrix between the encrypted images and the key images was calculated according to the encryption equation

the decrypted images are then obtained by ignoring the smaller correlation matrix between the original images and the key images. The results of computer simulations and performance analyses demon- strate that the proposed method can provide much higher quality and much faster speed compared to the BSS decryption

and also can directly decrypt varied images.