Just noticeable distortion (JND) is widely employed to describe the perception redundancy in the quantization-based watermarking framework. However, the existing JND models are generally constructed to treat every region of the photograph with an equal focus level, whereas the defocus effect has never been considered. In this paper, the defocus feature, which can portray the aesthetic emphasis in the photograph, is provided to improve the perceptual JND model. Firstly, two indicators which consider the block energy in the defocus measurement (DM) are proposed. Then, the defocus feature map (DFM) is obtained by integrating the influence of the circumambient blocks, and it is applied to the proposed JND contrast masking (CM) processing. In this way, a new blind photograph watermarking method, with emphasis on defocus-JND estimation combined with the proposed CM, is presented. Simulations show that the proposed JND is more suitable for watermarking framework than some exiting JND models, and the proposed watermarking scheme with the improved defocus-based JND model has superior robustness compared with some watermarking schemes.

中文翻译：

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基于鲁棒散焦的JND模型的盲照片水印

只是可察觉的失真（JND）被广泛用于描述基于量化的水印框架中的感知冗余。但是，通常将现有的JND模型构造为以相等的聚焦级别处理照片的每个区域，而从未考虑过散焦效果。在本文中，提供了散焦功能，可以在照片中体现美学上的重点，以改善感官JND模型。首先，提出了两种在散焦测量中考虑块能量的指标。然后，通过整合周围块的影响获得散焦特征图（DFM），并将其应用于提出的JND对比度掩蔽（CM）处理。这样，一种新的盲照相水印方法，重点介绍了散焦-JND估计并结合提出的CM。仿真表明，与已有的JND模型相比，所提出的JND更适合于水印框架，并且与某些水印方案相比，具有改进的基于散焦的JND模型的水印方案具有更好的鲁棒性。