Format-compliant perceptual encryption method for JPEG XT

High dynamic range (HDR) image allows more details to be seen in a digital image, where objects in the darker (e.g., shadow) and brighter (e.g., sky) regions are made more visible. Therefore, there is an increasing number of devices that include the HDR imaging capturing capability. In this work, a method is put forward to encrypt high dynamic range image encoded in the JPEG XT standard. To achieve diffusion, DC coefficients in the base layer are shuffled in groups of variable sizes. Similarly, AC coefficients in the base and residual layers are shuffled in the form of (zero-run-size, value) pair. Our encryption method is able to achieve: (a) suppression of bit stream size expansion, (b) sufficiently mask the visual appearance of an HDR image, and (c) format-compliant. Experiments are carried out to verify the basic performance of the proposed method. In the best case scenario, an HDR image can be completely distorted to mask its perceptual semantics with slightly reduced file size.