Flexible spatial locationbased PVO predictor for highfidelity reversible data hiding Abstract   An advanced predictor offers the most effective way for performance enhancement of predictionerror expansion (PEE) based reversible data hiding. Unlike conventional predictors which exploit the correlation among adjacent pixels, pixelvalueordering (PVO) exploits the one between the largestsmallest two pixels within block regardless of where they are located. Later, the spatial location received the attention from Peng etxc2xa0al. and led to better expansion bins selection. In this paper, a flexible spatial location (FSL) strategy is proposed to optimize the utilization of spatial correlation in PVO prediction. With FSL, pixels within block are no longer collected in a fixed way (e.g., from top to bottom, left to right). Specifically, eight modes of defining spatial location are designed for pixel collection. After pixel sorting, the inverse number of the location sequence is used to evaluate all modes and determine the best one. By determining the optimal mode for each block, the prediction becomes adaptive and thus a predictionerror histogram with higher expansion bin will be obtained. Numerous PVObased schemes will benefit from FSL. In this paper, how FSL is applied to conventional PEE and highdimensional PEE is also introduced. Experimental results demonstrate that FSLPVO is of great significance to better capacitydistortion tradeoff.

Perceptionbased Reversible Watermarking for 2DVector Maps This paper presents an effective and reversible watermarking approach for digital copyright protection of 2Dvector maps. To ensure that the embedded watermark is insensitive for human perception, we only select the noise nonsensitive regions for watermark embedding by estimating vertex density within each polyline. To ensure the exact recovery of original 2Dvector map after watermark extraction, we introduce a new reversible watermarking scheme based on reversible highfrequency wavelet coefficients modification. Within the formerselected nonsensitive regions, our watermarking operates on the lowerorder vertex coordinate decimals with integer wavelet transform. Such operation further reduces the visual distortion caused by watermark embedding. We have validated the effectiveness of our scheme on our realworld city riverbuilding 2Dvector maps. We give extensive experimental comparisons with stateoftheart methods, including embedding capability, invisibility, and robustness over watermark attacking.