Abstract
In this work, the authors construct a new algorithm to encrypt images of grey-scale type. After the decomposition of the image into 8 bit-planes, the key-image for the encryption and decryption algorithm are got by the representation of the 8 bit-planes in the new introduced basis. The decryption is done by subtraction between each encrypted image and key-image to obtain the 8 bit-planes from which we can restitute the original image without loss of information. The effectiveness of our proposed scheme is confirmed by some experimental results.