Hiding information in images

We present a new method of embedding information within digital images, called spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. SSIS conceals a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using the appropriate keys without any knowledge of the original image. Image processing, error control coding, and spread spectrum techniques used to conceal the hidden data are described, and the performance of the technique is illustrated. The message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, hidden communication, image tamperproofing, authentication, invisible map overlays, embedded control, and revision tracking.