Reversible Watermarking Algorithm of Grid Map Based on Prediction-Error Histogram

Reversible watermark is a kind of fragile watermark, and any changes will lead to the change or loss of watermarking information. The modified sensitivity of reversible watermark can be used for the integrity verification of grid map. When the content of carrier data is suspected, the type of manipulation or attack suffered can be judged through extracting the watermarking situation. The reversible watermarking algorithm proposed by this paper aims at the characteristics of grid map, to reduce the impact of low correlation of adjacent pixels, and the pixel values are distributed more intensively after the disposal of prediction-error histogram, thus to increase the embedded capacity. Under the premise of assurance of embedding capacity, there are 3 kinds of changes of pixel values, i.e. -1, 0 and 1, the change of source image is almost invisible, and watermark capacity can be repeatedly embedded. The algorithm simplifies the embedded process, and increases the embedding capacity, so that the complete-undamaged recovery of original image can be achieved.