Estimation of Watermark Embedding Capacity with Line Space Shifting

Abstract

The article describes an analytical model of the maximum achievable embedding capacity evaluation for robust watermark based on the approach to information embedding in text data by line space shifting. The developed model allows to boundary values assessment of information amount that may contain a watermark embedded into text data printed. In the developing process of an analytical model, the dependence of maximum achievable embedding capacity on the lines amount of a text document and the used watermark embedding parameters was established. The relationship between the parameters of a text document and the lines number per page of a text document is mathematically described. Mathematical calculations of the obtained expressions and the corresponding experimental researches are conducted. The evaluation of obtained simulation results correspondence to the parameters of texts printed on paper is implemented. The simulation results are analyzed and a linear dependence of the results is established. The obtained values are approximated and analytical expressions that allow one to quantify the maximum achievable embedding capacity of the developed robust watermark depending on the embedding parameters used are received. The degree of contradictions between the following parameters of robust watermarks: embedding capacity, extractability and robustness is estimated. The relationship between the maximum achievable embedding capacity and the accuracy of the extraction of the developed watermark is determined. Quantitative estimates of the influence of the size of the watermark on the final extraction accuracy of embedded information are given. The further research directions are determined.