A portion of an image is selected as an arbitrary rectangle indicated by
diagonal coordinates, and this portion of an image is encrypted and
embedded in the original rectangular image portion, thus accomplishing
partial encryption of the image. This is done by an image encryption
device, in which an partial image data selector, encryptor and decryptor
are connected via a memory; and a display, auxiliary (external) memory,
keyboard, mouse, image scanner, camera, etc. are also connected. At the
time of decryption, the encrypted rectangle is decrypted and returned to
its original state.
