2.1.2. J-Uniward

J-Uniward [9] is a method for modeling steganographic distortion caused by data embedding. It aims to provide a function that determines which regions of the cover object are less predictable and harder to model. Changes introduced during steganographic data embedding in those areas are harder to detect than if they were introduced uniformly across the carrier. Through computation of relative changes of values based on directional filter bank decomposition this method is able to detect smooth edges that are easy to model. By detecting these predictable and unpredictable areas, this method provides a way of determining where embedding changes would be least noticeable. This method is paired with a coding scheme, such as syndrome trellis coding (STC), to create a content-adaptive data-hiding algorithm.
