Encryption of visual data is an important topic in the area of mutimedia security, applications range from digital rights management to secure personal communications. This volume provides a unified overview of techniques for encryption of images and video data. This ranges from commercial applications like DVD or DVB to more research oriented topics and recently published material. This volume introduces different techniques from unified viewpoint, then evaluates these techniques with respect to their respective properties, such as security and speed. The authors experimentally compare different approaches proposed in the literature and include an extensive bibliography of corresponding published material.